yes but don't damage the face of the bolt, or it could potentially allow oil to seep through. is there enough room to squeeze a sacrificial something (like a bit of plastic off a milk carton or tin from a can) between washer and bolt to help minimise damage to bolt if the hacksaw goes too far.
The VAG sump plug (assuming that's what it is) has the thread rolled on, making the aluminium washer captive.
Reuse it if the washer is flat, unmarked and the hole isn't elongated. I like to smear some blue Hylomar on too. Don't overtighten - the sump is alloy, the plug steel.
John