Translations:Manage user groups/76/en
From LimeSurvey Manual
Removing permissions of a user no longer in a user group
Removing him from the group should leave him without any user group permissions. However, this is not happening due to the limitations of the user group functionalities! If you delete the user from the user group, he or she still remains with the user group survey permissions. Therefore, a workaround is to manually delete the account from the 'Survey permissions' table.