Justs throw the stuff out and dont donate anymore money to that charity. Eventually they will drop you on their own. You can also send the stuff back with “return to sender, addressee not known” on it (as if you had moved) but few will still bother taking you off the list – I’ve tried.

stop donating to charities that sell your info. they are using you in more way than one. you need to donate to more reputable organizations.

Read the fine print of the email. It should give you an address and instructions on how to if not just go to the website and usually there is a link to get your name off that specific mailing list