sed to remove last 2 characters of txt file

sed 's/^..//' file1.txt > file2.txt
this will remove the first two characters of each line of a text file, what sed command will remove the last two characters? This is a similar post to my other....sry if I'm being lazy....

I need a file like this (same as last post)
>cat file1.txt
10081551
10081599
10082234
10082259
20081134
20081159
30082232
10087721
>
to look like this:
>cat file1.txt
100815
100815
100822
100822
200811
200811
300822
100877
>

Already answered in the other thread.
Closing it.