Complex sentence: Whilst the majority of the those former ABC cinema which remain open are now branded as Odeon one member of the chain had retained the ABC brand located in Bournemouth, and on Glasgow's Sauchiehall Street the O2 ABC Glasgow is now a music venue.
Split into simpler sentences: Whilst the majority of the those former ABC cinemas which remain open are now branded as Odeon, one member of the chain, located in Bournemouth, has retained the ABC brand name. On Glasgow's Sauchiehall Street the O2 ABC Glasgow is now a music venue.