Recommendation for removing stuck bolt in bumper

[Missyblue]

Hey all just curious for advice. Have several bumper bolts in my bumper bullet to bumper where the locking nut you can't get a tool to is broke off and so the bolt just spins. Worried if we try and melt off it might damage chrome and curved bumper makes cutting seem challenging. Grind maybe? Curious if you had any suggestions and ideas. Thanks!