Every website is crawled by Googlebot at regular intervals. Google checks whether there is new content on the page or whether the website still exists. If you subsequently set a page to "noindex", it will only be removed from the index with a time delay. However, it is not possible to name an exact time window in which the adjustments are taken over. On average, according to Google, the pages are visited and crawled again after 6 months at the latest. However, this factor is highly variable, because the visit frequency for URLs by the Googlebot is related to an algorithm specially designed by Google. Depending on the importance of the URL, the change may already have been accepted after 14 days.