How Does oracle delete users and provide solutions?

When deleting a user in Oracle, the following statement is prompted: ORACLE cannot delete the current connected user:

SQL code
SQL>Copy codeThe Code is as follows: select username, sid, serial # from v $ session;

Username sid serial #
--------------------------------------------------
1 1
2 1
3 1
4 1
5 1
6 1
7 1
SYS 8 3
A 9 4
Nine rows have been selected.
SQL>Copy codeThe Code is as follows: alter system kill session '9, 4 ';

The system has been changed.
SQL>Copy codeThe Code is as follows: drop user a cascade; // Delete the user and all objects in the user tablespace

The user has been discarded.