depends on the type of glass – if its tempered safety type glass it’s a doddle. The cheapo horticultural glass is basically wafer thin sh*t and snaps if you breathe on it – although inexpensive to replace easily. Getting the hang of the clip things is a bit tricky – try using a flat bladed screwdriver – but be careful around that glass 🙂
Once the glass is out the alu frame is very light to move – but also twist out of shape, so i’d enlist a helper.
took me two hours to totally take down mine last weekend – including dismantling the frame.
And yes – getting it square is key – measure from corner to opposite corner – once it’s the same distance from each corner you know you’re square and can begin putting the glass back on.