Ngons and clean the mesh

I would like to know how to clean my mesh when I apply all modifiers :

How to clean my mesh well when there is bevel like in this situation. I hope I use the right method.
I would like to delete Ngons.

Thank you so much !

Bin it, and start again.

door_model.blend (527 KB)

Your method is good ! Thank you !
But I would like to use my method too.

Your method is bad practice. Get out of it.

Whats the problem again?