Any way to force backlinks to fall off?

I have a client that stiffed me on monthly payment (I know get paid upfront). I took his site from #48 to #1 for 4 or 5 months. I control 90% of his good backlinks and have removed his backlinks from each site last month. But, 30 days later and those same backlinks are still "counting" for his site.

Does anyone know how I can force the SERPs to notice that the backlinks no longer exist?

This is an interesting problem. Haven't seen this sort of thing on BHW so I'll bump.

How long has it been since between when you checked the backlinks and SERPS and when you removed the links?

It was the first week of May when I removed the backlinks, so right at 30 days now.

I figured it would take a few weeks for them to fall off but no movement at all thus far. Very frustrating as this is my first time with a non-paying customer and trying to "undo" my work for them.

Ping the site alot and than just let it go man, don't waste more time on it.

If you have done blast for him ,then it would be difficult to remove,if you have done manually ,it will be far easy because you might have been done only few backlinks.