Find the hole/slot in the front and slide a flat head screwdriver in the slot. Basiclly all that is holding it in place is a big staple, use the srewdriver to pry it out of there and pull knob off--watch for parts to fall.
To reinstall I find it best to use a visegrip to clamp the "staple", for it boes a bit at the ends, while you reinsert.
If all else fails get a bigger hammer!
93 SC Tbird
MPII w/ Plenum,90mm MAF, 85mm TB, 40# Injectors, 255 lph FP, Double IC w/fan, SCT Chip (Tuned by Jerry),3/4" Raised Top, F52-TT TC, SilverFox AOD 550, SPT-R VB
96 1/2 XR7 Sold and Salvaged
93 5.0 Tbird