Unknown helper - can't remove access
I do not have the option to remove helper access on the website. I see a person from Uganda made changes to my tree and I can't remove her. I have not given access to others to change my tree.
This is one world tree. Anyone can make changes to your ancestors.
If you had an LDS helper, someone else can talk to the process of ending that relationship as I am not a member of the LDS Church.1
If someone is signed on as a helper for you, all changes will have your name on them. Since you can see the other user's name, then that person was not signed in as a helper for you but was just acting as any user can in working in this wiki-style, universal tree we are all in together.
Were the changes appropriate? Were the changes wrong due to innocent confusion of people? Were they blatantly strange? Does it appear this other user is confused and also thinks he or she is also working in a private tree? Does this other person have Relationship viewing turned on? Have you tried messaging the person?4