How do you delete everything outside an outline?

[S1mthi]

I have a profile picture of someone and wanted to put a png behind it, so i outlined the right side of the person's head (the picture is only of the person's head, and the head gets cut off on the top and bottom, so I only erased the outline around their head) 

 

How do I delete everything on the right side of that outline (everything on the right side of the erased area)?

[toe_head2001]

The Lasso Select () tool works. Select the region, and then press the Delete key.

 

You can also try TR's Alpha Cutter plugin.