Remove 1 letter from text without moving it.

[Ofnuts]

An even more accurate technique if you still have the text layer

• From the text layer: Layer>Text to path
  
• Edit the path with the Path tool, removing the two strokes that make the O
  
• Select>From path
  
• Bucket-fill the selection on a new layer
  

I also have a script to split the text path into its letter components, with it that would be only a matter of splitting the path, deleting (or making invisible) the path of the letters you don't want, and then merging the paths again.

It is also possible that you don't need to delete the character at all... what is the initial problem?