Lawgill, removing the levelwind might gain you 5-10yds on your cast, removing the brake blocks, servicing the bearings (with carbon not grease), using light oil instead of grease, & rubbing Mucilin on your line, changing to ceramic eyes on your rod will gain you at least 30yds! but do you need to?
If you have had this 6500C for 30 years the same as me, you will be casting without using the brake blocks, & getting all the distance you want, plus you dont have to spread the line across the spool on the retrieve, you will achieve nothing.
If you want to go tournament casting & need the extra 5-10yds, then to remove the levelwind, remove the left hand plate (the opposite side to the handle) by unscrewing the 3 small screws, this will reveal the levelwind mechanism. There is a flat plate with 2 recesses that holds the mechanism in place, remove that & the entire levelwind sytem comes off in 1 piece.
If you want to be really ruthless remove the nylon levelwind drivewheel, this will cut down on any imagined drag!
Remember how it came off, & put it safe, you will want to put it back on very shortly!
blueskip