How to remove headlight LENS on 1999 Grand Marquis

How the heck do you remove the headlight LENS on a 1999 +/- Grand Marquis /Crown Vic'???!!!

I removed the four metal clips, and made my best attempt to remove/cut-away the sealant (Sylicone, or whatever it is)...Though I can't seem to get to the sealant that's UNDER the clear lens-- between it & the headlight housing.

I imagine that's the problem-- Removing the sealant, that I can't get to but, if that's the case, why do they bother putting the four metal clips on there???

I need to get inside the housing so I can clean-out the dirt inside... And yes, I've already tried removing the headlamp & turn signal, then blowing it out with an air-gun/compressor. That did remove a small ammount of dust but, there's still a bunch o' dirt that I cant "blow-out"(!)

Thanks, in advance!
Lt'C
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MEDICAL MARIJUANA PATIENT (http://mmjp.org)