Can I withdraw my H1B Petition and continue with the GC Processing?

Hello,
I am currently holding an L1A VISA from my current Company X and applied for H1B through
another Company Y. H1B Petition was a fresh one for Year 2015.Currently, I have received RFE on that petition and replied to the RFE.
Now, I came to know that my current Company X is going to process my GC and I would like to avail that.

Can I withdraw my H1B Petition and continue with the GC Processing? What’s the issue if I don’t use the H1B if gets approved?

Thanks,

Was your H-1 filed w/ COS?