.tutor-field--optional { display: none; }
.tutor-field--optional { display: none; }
<table class="availability">
    <tbody><tr>
        <td class="no-border"></td>
                    <th>Pre 12pm</th>
                    <th>12-4pm</th>
                    <th>4-7pm</th>
                    <th>After 7pm</th>
            </tr>
            <tr>
            <th>Mon</th>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                    </tr>
            <tr>
            <th>Tue</th>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                    </tr>
            <tr>
            <th>Wed</th>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                    </tr>
            <tr>
            <th>Thu</th>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                    </tr>
            <tr>
            <th>Fri</th>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                    </tr>
            <tr>
            <th>Sat</th>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                    </tr>
            <tr>
            <th>Sun</th>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                            <td>
                                                                                    
                </td>
                    </tr>
    </tbody></table>