Clutch cover pressure plate assembly hold down bolts to assist ease of installation not removed.
Remove hold down bolts.
Clutch cover pressure plate assembly contaminated with oil.
Only clutch disc was replaced which caused a vacuum not allowing the clutch disc to separate from the clutch cover pressure plate assembly casting, when clutch is in disengaged position.
Always replace clutch disc/clutch cover pressure plate assembly and clutch thrust release bearing when replacing clutch system.