MySQL Workbench
If you want to avoid writing sql, you can also do it in MySQL Workbench by right clicking on the table, choose "Alter Table ..." in the menu.
When the table structure view opens, go to tab "Options" (on the lower bottom of the view), and set "Auto Increment" field to the value of the next autoincrement number.
Don't forget to hit "Apply" when you are done with all changes.
PhpMyAdmin:
If you are using phpMyAdmin, you can click on the table in the lefthand navigation, go to the tab "Operations" and under Table Options change the AUTO_INCREMENT value and click OK.