The full-text index of a database can not be deleted when index creation/updation is being carried out.
When the user tries to delete full-text index of a database during the time, user gets a confirmation prompt to delete the index. However. the full-text index(****.ft) will not be deleted for the database.
In this case user assume that the index is deleted for a respective database.
If the full-text index creation/update is in progress and the user tries to delete the index of a target database, the respective user should get the message such as : "indexing already in process, please try after some time" etc.. to avoid confusion.