Actions available for the filters and subscriptions
The app provides the Jira admin ability to perform different actions to the filters and subscriptions of all Jira users. If you are going to delete or manage user filters and subscriptions ensure the user was acknowledged in advance. Each tab (excluding the Duplicates filters one) allows users to perform different kinds of actions to the tab entries.
Filter validation
Check if the filter query is valid by selecting the Validate option in the entry action menu.
The following are the examples of validation results (for valid and invalid filters). For a valid filter you will see the pop-up that disappears automatically. For an invalid filter you will see the pop-up with the message describing the reason of the filter invalidity. Such message won't disappear automatically to allow you to investigate the problem.

Subscription management
Go to the filter subscriptions by selecting the Manage option in the entry action menu.
You will be redirected to the page containing the filter subscription and will be able to add a subscription, manage the existing ones, and/or delete them.
Filter name and owner editing
Change the filter name and/or owner by selecting the Edit option in the entry action menu.
This option may be useful when the filter belongs to an inactive (check the All objects with inactive owner tab) user but still being in use by others.
Filters and subscriptions deleting
Delete the filter/subscription (depends on the selected entry) by selecting the Delete option in the entry action menu.
When deleting a filter the relevant subscriptions will be deleted automatically, so check the subscriptions first by selecting the Manage option.
Mass deletion
The mass deletion is available both for filters and subscriptions. Tick the checkboxes for the entries you'd like to delete and select the Delete selected option in the right upper menu. You can select all page entries at once by ticking the upper panel checkbox.
When deleting a filter the relevant subscriptions will be deleted automatically – check the subscriptions first by selecting the Manage option.
Searching by a piece of JQL
The Filter button allows you to find all filters (and relevant subscriptions) that contain the required text in any place of JQL-query.
It's a great feature, for example, if you are going to split the projects and would like to find all filters where this project is mentioned.
Don't forget to Reset the filters afterward.