2 photoshop issues asap

im trying to make a mock up of a glass frame, I downloaded a file from adobe stock and for somereason the transparent background of grey checks is attached in one file with no layers, I tried to get rid of it by doing a mask but it doesnt work for under the glass. Anyone know what to do.

2 I downloaded another one but it won’t let me place a picture on the frame for some reason it keeps on bringing me a layer within the file that I keep trying to delete but it doesn’t work can some one help me

Sounds like they are illustrator mockups opened up in photoshop?

oh ok thank you