Hook for removing a role from a user Specifically, when an admin goes to the 'People' admin screen, selects some users, then goes to 'Remove a role from the selected users', I want to capture this and apply some other actions.

To give a little bit of insight into what I'm doing: I have another set of tables in the same database belonging to a CRM, and when the user is removed from xyz group, it should toggle the account status in the CRM as well. The action of toggling the status is no problem, I just need to know the best way of going about capturing the role removal. Is there a quick way of doing this, or am I going to need to create a new cancellation method via hook_user_cancel_methods_alter()?
You can use Rules module for it. There is an event "After updating an existing user account", add conditions "User has roles" (both for account-unchanged and account parameters to check roles before and after an update), and as a action you can use "Run custom PHP code" to do whatever you want.