How do i tell my locker partner she needs to move out?

So it's 8th grade and we get our own lockers. But my friend, Houston, yes she's a girl (she was my locker partner last year) moved into my locker because her original one is too far away. she takes up a lot of space and i have a lot of stuff. i need my whole locker. but she's so sweet and i dont know how to tell her she needs to go back. should i say "Houston, i don't know how to tell you this, but i think you need to move back to your own locker. i need the space." or what? something? i dont want to hurt her feelings and i dont want to make her mad (as she has my combination, and could steal my stuff, give it to someone untrustworthy, etc... ) ive been hiinting at it a lot and she's just like, "well make room." "i dont usually have this much stuff." "blahblahblah."