We always advise our users to pause irrelevant search terms and not remove them. By pausing the search terms, you ensure negative keywords are present in other ad groups to avoid the ad to be triggered.
For e.g., If we take a scenario of 2 search terms "ads software" and "free ads software". Instead of removing "free ads software" it is recommended to pause it. It will ensure free as a negative keyword in ads software ad groups thereby avoiding any irrelevant searches from that ad group.
Please note that pausing an ad groups will not add it in the shared negative list. After you have paused the search terms, it is also recommended to add negative keywords to a shared negative list and apply it across campaigns. For example, in the above case, you do not want to show ads for "free" related keywords. When you pause the search term 'free ads software', any search query related to this keyword (in all exact, phrase and broad matches) will not trigger ads. However in the future, since we detect new search terms during maintenance and add them to the campaign, we might add a keyword saying 'free ads tool'. 'free ads tool' might be a keyword which you do not want to advertise. So it's better if you add 'free' in the negative list to never trigger ads for such keywords. You should add 'free' as a broad negative keyword in the list and apply to the campaign. Learn more about adding negative keyword lists here.
Please note the system will not create any child keywords of 'free ads software' since you have paused it.