Hi, can anyone help me please?
I was trying to format my friend's thesis, but the document he send me has this weird box in the upper right corner of EVERY page. It's not a text box, it's not a inserted shape or image. I tried everything to delete it and can't find anything about it online... Does anyone knows what this problem is and how can I get rid of it?

(I have captions of it but I wasn't able to post them here)

Thank you so much!