Option 1
history | cut -c 8-
It’s deleting the first 7 characters of each line of output of the history command. It should only have problems if the number exceeds 99,999.
Option 2
history | sed 's/^ *[0-9]* *//'
Option 3
history | sed "s/^[ \t]*//" | awk '{$1=""}1' | sort -u