Hello Marina,
Greetings.
For any Office 365 for Business accounts users, their admin can help them to remove the uploaded photo via the PowerShell command: Remove-UserPhoto, and after running that command successfully, they will see the initial photo.
So in your case, please involve your admin to help you do it, for your admin reference:
- Connect to Exchange online
- Get-UserPhoto -Identity "<identity>"
- Remove-UserPhoto -Identity "<identity>"
Thanks for your time and hope it helps.
Please do take care.
Regards,
Rudy