KSC G19 Metal Slide
 

Hey guys i just installed a G19 Metal Slide. But the Rear sites wont come off the original plastic slide. Does anyone know if it can be removed?

You should be able to take it off, it's listed as a separate part:
http://tech.airsoftcanada.com/KSC/ksc-g19s.jpg

slide them off from one side or the other, usualy to the left if you are holding the gun normally.

If you bought the gun used there's a chanced the site is glued on by the past user cause they're well known to just fall off during use.

Use a small hammer and a punch to tap the sight off.

Thanks guy I did not think i needed to actually use a Hammer. My sight was very very tightly stuck in.

I've owned numerous Glocks with rear sites stuck on even with glue. I just got a cloth to cover the tip of a screwdriver and then I tap it with a hammer and ease it out. Works everytime and without getting it gouged up.