Priority is not the same as severity.

1 how do i rename priority levels?

2 how do i remove a collaborator?

having trouble with that too. is there a solution?

I second that. For me the names are not important, but I would like to see 10 levels of priority.

I agree. If nothing else change the numbering order. Typically a "number 1 priority" is the highest priority. It has always been counter-intuitive wrapping my head around #3 being "Top" priority. But would still much rather see customizable priorities..

This should be joined with the 'rename priority fields'

I second Wayne T.'s suggestion. So much of this interface can be customized already; it seems like this would be a natural step.