Pascal Hambourg composed on 2017-12-03 23:40 (UTC+0100):
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Then, to proceed, remove /dev/sda1 partition followed by grub-install?
Removing the partition won't help. It is just useless, it does not harm.
If sda1 is a type EEh partition, doing that will probably dig your hole too
deep to escape from, absent a full partition table wipe. :-(
What are you talking about ? ee is the identifier for the GPT protective
partition in the MSDOS partition table of the protective MBR. This
partition is hidden. I am talking about the only real sda1 partition
that is visible, the one defined in the GPT partition table and is shown
by fdisk as "BIOS boot". Please do not make things even more confused
than they are.
To imply that removing a type EEh sda1 might be innocuous and use the term "real
sda1 that is visible" (visible how, in what context(s)?) is to interject
additional confusion.
With its removal, sda2 might, depending on the details of
how it was done (how many different partitioning tools have already been
employed on OP's MBR sector?), become sda1, sda3 become sda2, etc., in addition
to voiding its protection and possibly invalidating the table.