importing new images into LR old session comes up with my new sessions images slowly opening over them.
All enhancement from the old session happen to new files.
I thought it was my card not formatting properly but now realized it's lightroom
Can I delete all old cataloges?
Can you explain in more detail? What does "with my new sessions images slowly opening over them" mean?
I would not delete any catalogs.
Sorry to say but this is, at least to me, User Error in some way. If you have a memory card inserted in a card reader and call up the Import dialog window the only images LR sees is what is on that card. If you are seeing older images then you didn't format the card before taking new images.