Orphaning a package
If you can no longer maintain a DebianPackage, you need to inform the others about that, and see that the package is marked as orphaned.
How
You should:
set the package Maintainer field to Debian QA Group <packages@qa.debian.org>
upload the package with this Maintainer change
submit a bug report against the wnpp pseudo package.
The bug report should be titled:
O: package -- short description indicating that the package is now orphaned
It’s recommended to run reportbug wnpp, choose option 2 O and let reportbug guide you through.
Severity
The severity of the bug should be set to normal; if the package has a priority of standard or higher, it should be set to important.
Informing the debian-devel mailing list
If you feel it's necessary, send a copy to debian-devel@lists.debian.org by putting the address in the X-Debbugs-CC: pseudo-header of the message (no, don't use CC:, because that way the message's subject won't indicate the bug number).
Propose for adoption instead
If you just intend to give the package away, but you can keep maintainership for the moment, then you should instead submit a bug against wnpp and title it:
RFA: package -- short description
RFA stands for Request For Adoption.