Shared mode

here is the fix 

For SQLite

1. Download and install the SQLite Browser utility.
2. Close P6 Professional.
3. Open SQLite DB Browser.
4. Select Open Database and navigate to the SQLite database

Database Location

C:\P6localDB\Mydatabse.db or wherever yours is located and named.

5. Run the following queries: by selecting the tab Execute SQL

delete from projshar;    Then press the play button



delete from usession;    Then press the play button

6. Click Write Changes then close the utility.

7. Login to P6 Professional and test.

You can probably clear the phantom user using "DB Browser for SQLite"