Qlik Sense does not allow you to delete variables from the script. However, you can reuse them or assign new values as shown in the following block:

SET vMyFirstVariable = 'First value';

SET vMyFirstVariable = 'Reassigning a value';
//Assigning an empty variable most probably means we don't use this variable anymore.
SET vMyFirstVariable = '';

Even after assigning an empty value to the variable, it will remain in the application. You can only delete variables from the Variable overview in the application.

Keep reading to find out more about variables and how to use them in your application.