A single value?

Open the kerning list in the Kerning Panel (second buttom from the right in the panel's toolbar).
Navigate to the exception pair. Alternatively, type the pair into the preview part of the panel and click on the right glyph of the pair; this will highlight the pair in the kerning list.
Click on this kerning pair's line in the kerning list; do this even if it is highlighted already!
In OSX, hit the 'back' key. In Windows it might be the 'delete' key, I don't know.

My god – it works!

Thanks SO much, I've been struggling with this a few times before.

All the best Karsten – my hero.

A follow up:

Could you do this automatically for ALL exceptions? That would be even better in this case.

It's here, "Remove Exception Kerning". It is important that you open the script in a text editor first and assign your own identifier tags which identify your classes as leftside, rightside (and exception). Else the script won't work. Also see the notes in the text file. Not tested much, so better try with a copy of the font first.  :)

Kerning pairs of which one glyph is not covered in any class at all are not considered exception kerning pairs!

Karsten is da MAN!

ChrisL

Karsten – Did you just wrote a script for that?! :)

Halleluja, I go ahead and try it. Many thanks.

Interesting that FontLab doesnt have this feature in built in the program, btw. I think it should be there.

A bit late, but in version 5.1.3 it appears you can right-click on a glyph(pair) in the Metrics window (in kerning mode) and reset kerning from this menu. Then you can choose the range on which to apply it.