How do I sew a "Sleeveless"-shirt? [PIC] Sewing Machines Parts and Sales in Los Angeles

Hi friends.

I’m a beginner at this. I want to re-make some of my shirts with an oversized fit to a style called “Sleeveless/Oversized”. Look at pic for reference.

How should I go about it?

On my previous shirts I just roll the sleeves and nail them. However this creates a “tight”-feeling on the arms as well on the sides of the chest. Do I need to cut open below the armpit? Any input would be greatful…