[Edit profile. Professional info] Verify that the user can clear the "Main study category field" in the "Your professional category" pop-up.

[MilaKomisarenko]

Test case verifies the flow for a Tutor and a Student simultaneously that when the user can clear the "Main study category field" after selecting a category.

Preconditions:

1. The user is logged in https://s2s-front-stage.azurewebsites.net/tutor as a Tutor/Student.
2. “My profile” => “Edit profile” => “Professional info” page is opened.

Test steps:

1. Click on the “Add category button”.
   Expected result:
   The “Your professional category” pop-up displays.

2. Select the main study category.
   Expected result:
   The category is selected.

3. Select the category subject.
   Expected result:
   The subject is selected. The button "Save changes" is enabled.

4. Clear the category by clicking on the "X".
   

Expected result:
The category and the subject are deleted. The button “Save changes” is disabled.

User story link [Edit Tutor's profile. Professional info. # 2694] (#2694)
[Edit Student's profile. Professional info. # 2695] (#2695)