This is a standard procedure in many forums, Im surprised it isn;t the case here.
First of all, threads which have become bickering need to be stopped. I understand that and it is stated in the forum rules. Removing useless threads or agressive threads that serve no purpose except lashing out is what a good mod should do.
HOWEVER, In some of these threads there is often useful information for the community which is lost if the thread is deleted.
To avoid this situation almost all forums close toxic threads with a message stating why they got closed and that they will be deleted in 2 days for example.
This allows the people to salvage the useful information from the thread and make a new one if needed. Like it was the case for the ninja fragments in survival breakthrough.
My suggestion is simple:
Before removing a thread, close it while saying why it was closed (insults, outdated information, question answered, etc.). Then if the said thread violated the forum rules, in the same post, write that it will be deleted and do so after x days. The explenation can be a single sentence such as: "the conversation has become toxic and violates TOS or forum rules".
Deleting threads with no explanation whatsoever is aggravating and alienates *ready unhappy community even more. It also has the risk of deleting useful information or posts that DID NOT transgress any rules.