Complex sentence: After these great seasons, Apollon's glory started to fade and as a result, in 1999/2000 season Apollon was relegated in Beta Ethniki, in 2005 relegated to Gamma Ethniki (South Group) and in 2007 relegated to Delta Ethniki (Group 8).
Split into simpler sentences: After these great seasons, Apollon's glory started to fade and as a result, in the 1999/2000 season Apollon was relegated to Beta Ethniki. Then, in 2005 it was relegated to Gamma Ethniki (South Group) and finally, in 2007, to Delta Ethniki (Group 8).