Remove user from a role for a set amount of time

[Luffy-2]

All right so basically I'd like to know the simplest way of removing a user from a role for a custom amount of time. For example +roleBan <user> <time>. The role ID isn't needed since it will always be the same.

However, this role is self-assignable - how could I make it so it gets removed again if they assign it to themselves again, before the ban period is over?