I am reinstalling windows 7 but I cant put os on partition because it has an mbr partition table, but i can't delete it either. I cant repair because it is somehow not compatible.
If you are willing to wipe the disk clean, then boot from the Windows 7 disk and instead of an install, open the command prompt. Use diskpart to clean the disk:
diskpart
list disk
select disk n (where n = the disk you want to clean from the list disk command)
clean
exit
Now you have an unallocated drive that will be available to install Windows 7.