mmmm part off the problem is they usualy cut the frame centraly and break in towards the centre
you may be ok by realeasing the tiles as discused before as long as theres a point on opposit side of the frame where they can cut through and slightly beyond the edge off the frame as the blade will be longer than the frame
had to replace a 6" bargeboard last week on a garage with only 2mm between the corrigated asbestos and the top of the wood
my solution which worked a treat using a recip saw was
pull the blade fully out measure accuratly cut 2 lengths 2x2" 2mm longer than the measurement
affix the battons with the top edges level with the frame the width off the teeth apart
saw carefully you will have to work the blade tipping the blade in to fully cut the frame pulling the firmly held saw down to progressivly realease the frame
you will finnish up with about 5mm uncut at the tile edge you could if its visible cut this carefully a handsaw
now if the tiles or grout are touching the frame the act of levering or hammering the frame away may disloge or break tiles so tape the edges so any loose broken tiles can be reafixed
and dont forget they have flat plastic sections from about 12mm to several inches to cover disturbance where the windows where removed from
clear as mud eeehhh