Can I remove and replace barbed connector in 1/2" drip tube?
It is possible.

If the tube is old and brittle than you may crack it. 
If you do crack the tube, or you have to cut it, you can buy new inexpensive tubing  and barbed couplers as well. 

Heat it up with a hair dryer or hot water and slowly wiggle it back and forth as you pull. Some come apart more easily then others.