Rubbing out is a phrase that can be used to describe erasing something, removing a mark or even killing someone. However, there are many synonyms for this phrase that can help to communicate the intended meaning more precisely. For example, erase, delete, cancel, or obliterate can be used when referring to removing a mark or item. Whereas assassinate, eliminate, murder, or exterminate can be used when referring to killing someone. Similarly, words like erase, obliterate, grind away, or sand away can be used when referring to removing something physically. The choice of synonym will depend on the context of the sentence and the intended meaning that the writer wishes to convey.