What you need to do is remove the architraves, get a recriprocating saw with a metal blade. The timber reveals will, more likely than not, be nailed through to the timber wall framing behind. Start at top, being careful with the saw blade, cut down until you strike no more nails. Repeat on the other side & then across the head. With a bit of luck the brickie won't have fixed any veneer ties to the door, they do sometimes. Then often the plastic flashing will cause grief too. You now have to basically bash the door out from the outside inwards, hopefully carpet & or tiles won't be a problem! If they are, you will probably have to destroy the aluminium frame.
I do this type of thing for a living (construction insurance repair work) and this is one of those jobs that are usually a real pain in the arse!
Why is the timber water damaged? Blocked weep holes, overflowing gutters, roof leak? If the cause isn't fixed, you'll have to do it again sometime, or sell up & leave it to some other sucker.
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