Are you...
A Trap?? (revised from a Strap, which is a weaker answercough I mean it doesn't work.)
Reasoning:
"Be careful I'm dangerous, left how I'm read"
Traps are generally dangerous.
"Remove my first letter and I'll become music instead"
Rap is a type of music.
"Switch my middle letters and I'm used as a cover"
Tarp, short for Tarpaulin, is used as a cover.
"Leave me as a cover then take away my last letter, I'll become something flammable like no other"
Tar is very flammable.
Method:
Looked up types of music, found this, used brute force.