Welcome to Just Answer.
Sorry to hear about your problem.
Depending on the type, you either have clips that can be accessed by looking up behind the screen panels or fasteners behind a snap-on trim piece; see diagram by clicking here.
If you need further help or clarification on this answer, please do not hesitate to reply to this post.
Thanks for asking your question at Just Answer.
Best of Luck, Brian
Please leave feedback at your convenience.