It sounds like you're trying to hide projects in Jira Software cloud, based on your description. You can find instructions for how to do that here.
Note that the article says:
A 'hidden' project will still be visible to people with admin permissions; regular users won't be able to search, view or modify any of the project's issues.
So if you're still seeing the projects you hid, it may be because you're an admin.
Edit Nov. 6, 2020: Thank you for all your feedback. We’ve summarized and addressed your top concerns and questions on this thread. --- If you haven’t already read our recent announceme...
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