I seem to have 161GB of backups on my HD Macbook pro 17inch. How can I remove these as I am running out of space?

OS X Lion and Mountain Lion, with Time Machine turned on, make "local snapshots" in the internal hard disk > http://pondini.org/TM/30.html

When your hard disk gets full, Time Machine will delete local snapshots, so you don't have to worry about it. However, if you want, you can turn them off or delete them, even if you don't need it

Have a look at these 2 links...

Local Snapshots Laptops

http://support.apple.com/kb/HT4878

http://macmost.com/time-machine-local-snapshots.html

More Info here...

Where did my Disk Space go?

The Storage Display