replacing glass in patio doors alliminunm

had at a look at some old metal patio doors which 1 side has a misted up glass unit. The side with the misted glass is the non opener side
the glass itself is 16mm overall and measures from edge of frame is
1875mm by 795mm
advice im looking for how is glass removed and refitted and whats the possible glass sizes width and length would be
any help would be appreciated

Sounds like these windows could be quite an age. The old ones I took out were fixed together with a couple of long self-tapping screws on each corner: the whole thing knocks down to 4 glazing bars and the D/G unit itself. You need to lift the panel out to dismantle. Watch out - they can be very heavy. The ones I had were made from 2 sheets of quarter inch plate with a quarter inch gap between. The glass wasn't toughened or laminated so was potentially lethal and the gap so small as to be pointless.
Might be worth thinking about a replacement....