You have to tell him. If you are old enough to have a boyfriend than you better be old enough to break up with him, and to do so face to face. Sometimes growing up means you have to do things you don't like, but you do them because they are the right thing to do.
I agree with the above comment , if u are old enough to be Ina relationship , you should be muture enough to end it politely and in a non hurtful way . Good luck . Remember , treat the break up the way you would want one to treat you .
Just tell him it will be the best thing to do.If you do not want to be with him anymore there is no since in just being with him still whenever you really do not want to so break up with him.. you will be happier