KNOWN ISSUE: Slow deletion

Users conducting a large survey (millions of interviews conducted) reported slow deletion of the questionnaire (several days). During this all time the questionnaire appears in the list of the questionnaires in a disabled state:
https://support.mysurvey.solutions/faq/deleting-a-survey/

This is indeed the current behavior, because Survey Solutions attempts to delete one interview after another. This is recognized as inefficient and we will improve the software to perform the deletion faster.

Note also that deleting of a questionnaire is a relatively rare operation.