those screws are not needed. i have drilled them out on cars before. they are only needed on the assembly line to hold the rotor on the car before the wheel is put on.

having a small piece of the screw in there is no big deal, just ignore it.

to get off the rotor, take a hammer and hit it all around from the backside. this will break it loose and allow you to pull it off.

 

those screws realy suck I usually end up drilling the head off them

 

I would use a Sock It Out or something similar and clean out with a tap, if necessary. Just my opinion.

http://www1.mscdirect.com/CGI/NNPDFF?PMPAG...00&PMT4TP=*LTIP

 

i've used a screw extractor (attached to an impact driver) to remove those damaged screw heads. note mine still had the screw head in tact though. if the head is already gone, you might be able to pull the rotor off then remove the remaining screw threads w/ a pair of pliers.