We have several SharePoint only accounts that don't correspond to any users in our Active Directory. How can I exclude these accounts from People search?
I think you were looking for a way to remove the accounts from the search results? If so, you can create a crawl rule to remove them from the results. You can create a managed property for the account name and exclude it from the results.
In the User Profile Service Application, change the permissions on who can use the profile features (Manage User Permissions). Instead of the all users groups, change it to a group that includes only the users who should be using the profile features and such. Then re-run your search crawls.
You can also exclude the non-people accounts by creating the import connection so it only pulls from an OU with people. (Provided AD is set up with People in one OU and Service Accounts in a seperate OU.) If not you can add bitwise filters to eliminate the extra profiles.