I'd purchased internet security before, can i move to another computer?

Subject is Description
Can i?
and i’d delete computer that purchased internet security.

Short answer, yes.

Then, How?

  1. Uninstall on old machine.
  2. Reinstall on new machine.
  3. Enter license. Done.

I’m so sorry
but There is no license

If you purchased it then:
Try the Resend avast License http://www.avast.com/resend-license-paid.php, you will need to enter the email that you used when purchasing the license, e.g. the one that the original email with the link was sent.