Is it permissible to stop and restart a prayer due to obsessive thoughts and insults against Allah, and is it valid to delay prayer until one returns home because of that?

If the thoughts or utterances that are unfitting for Allah come to you involuntarily and you detest them, then they are merely satanic whisperings (waswas) that must be repelled, and you should not succumb to them. Repelling them is a sign of faith. However, if this occurs by your choice and you utter what is considered disbelief (kufr), then you must renew your Islam and repent to Allah. As for prayer, it is not permissible to delay or interrupt it due to these whisperings; rather, it must be performed on time, while disregarding the whisperings and maintaining devotion in it.