To answer your question yes, if you can get into BIOS then you can downgrade the BIOS version. Use QFlash and load the BIOS version that you want to go back to and run the update in the usual manner.
NOTE: This doesn't apply if you have updated your BIOS from Award to UEFI. If you have done this and wish to revert from UEFI back to Award it is a bit more complicated.