Can't get the whites edges to clean up

[Tom Snyder 4,113]

 

I'm having trouble getting rid of the white edges on this, i try to delete them; but it doesn't want to remove it. Can i please get some help with this? I'm using GIMP 2.8 to make this and i'm getting really frustrated.

[Dark Heart 284]

 

I'm having trouble getting rid of the white edges on this, i try to delete them; but it doesn't want to remove it. Can i please get some help with this? I'm using GIMP 2.8 to make this and i'm getting really frustrated.

Dunno about gimps Sry, but when i had this problem on the program i used its always due to "tolerance" or cliping depending on programs, but when i ran in this kind of problem and cant find a solution i just make the lineart ticker to cover the white edges, but its time consuming.