I guess the answer is obvious but just to make sure…would it be possible to remove the guitar from a song?
all the best from Italy
mic
Basically, no. 
You can experiment with the Vocal Remover effect, which subtracts left from right to remove everything in the “center” from a stereo recording. You can find a few more advanced tools that allow you to keep the “center” and remove sounds that are in only in the left and only in the right. These things can be fun to play with, but you rarely get anything "useful’ or “production quality”. And of course, you can always kill the left or right channel , keeping whatever side you want.
“You can’t un-fry an egg or un-bake a cake, and you can’t un-mix sounds.”
There’s nothing for the software to grab. People always point to the spectrum analyzer with the idea of separating higher and lower sounds. Musical overtones and harmonics step on each other and that’s why that doesn’t work. If you were playing music with laboratory tone generators, then yes. Those are pure and you can manage any tone or note as you wish. Singing and playing doesn’t work like that.
Vocal Remover kills anything the same between left and right. It’s strictly math. It has no idea what it’s really doing.
Koz
thank you guys for the reply. I thought it would be like this. and I already test try vocal remover but the quality, as said, goes too low to be used in professional environments…
mic