No need to remove in either case.
You do know you need 1 1/4" of subfloor for under tile? (this doesn't
include the non structural cement board underlayment). Some vinyl floors are
installed over only 3/4" subfloor.

"Perry Templeton" wrote in message
...
In applying cement board to the floor in order to install tile, do I need
to remove glued down 25 year old Congoleum? It is secure, the wood that
it is glued to is secure, so is there any reason why it can't just stay
right there?
Thanks.

Same question applying to installing click laminate flooring? (not about
installing a cement board, but about leaving the congoleum)

Perry