Background

Processes and procedures evolve, meaning that issue types available become insufficient or unnecessary at some point. For insufficient, one can create and add it to the necessary projects.

For the no longer necessary issue types, prevention of creation and usage from a given project (or completely) can only be done by moving away ALL existing issues of that type to a new one. This impacts history of past (closed) cases and changes their purpose at the time.

Suggestion

Allow archiving a ticket type in a project scope (at issue type scheme level?), keeping all existing occurrences (or at least the closed ones).

This archived state should prevent creation of new issues of that type. Note that the suggestion refers to main and sub-task issue types.