Administrator account recovery

[Alexander]

Good afternoon, colleagues. We have a project based on Jira, now we need to grant access to several colleagues to the project, but the project administrator account has been lost, tell me how can I restore access? The second question is, how can you remove unnecessary people from the project at the current moment? Thank you very much, do not judge strictly, I almost never worked with Jira.

[Chris Buzon]

If you lost the admin account you'll need to open a ticket with Atlassian for help.  There isn't a workaround for that because it would be a huge security hole. 

"removing unnecessary people" depends on whether you're using a Team managed Project or a Company Managed one.  Team managed is easier, you just go into the project settings and set it to restricted, then include only the people you want in it.  Company managed requires complicated permissions setup, beyond the scope of a post like this.  I suggest you look up the Permissions  setup for projects, it's quite a lot to take in at first.