I’m tearing some off of it would theoretically be translated to:

(incorrect:) J’en en arrache.

but this sequence of two joint pronouns (pronoms conjoints) is agrammatical.

Assuming you really don’t want to repeat any of the complements, the way to handle this conflict is simply to merge the pronouns in a single instance with what is called an haplology (haplologie), leading to:

J’en arrache.