hello,
Is it possible to make a mobile internal storage a removable storage ?

 

Depends on your definition of possible, internal, removable, and storage? In other words, a bit more information is needed to clear up my crystal ball...

 

Convert a phone internal storage (the phone is without battery) to removable storage such Flash disk

 

Only if the phone has already made this provision. I can't think of a way you do this without the phone providing for it. Do you imagine the manufacturer's want to make this easy for you?