ask: invalid ip>service>ssh

hello

i have rb750 was running ros 5.13, then its seem slower perf than usual so revert to 4.17

but i have small issue ssh service were said invalid (port normal 22)
error message:
“Couldn’t change IP Service - feature is not implemented (2)”

How can I see what key list on the ssh folder?
How can I remove unwanted ssh key?

BTW I had “sys reset”, but couldn’t fix the ssh service error

please assist… thank you

check this

http://forum.mikrotik.com/t/cant-enable-ssh-service/55007/1