Complete required steps:

$1$: Create a HTML form with the following input fields:

$-$ Session variable name $($text input field$)$

$-$ Session variable value $($text input field$)$

$2$: When the user submits the form, retrieve the session variable name and value using the $$\_$POST superglobal variable in PHP$.$

$3$: Set the session variable using the $$\_$SESSION superglobal variable in PHP$.$ You can set a session variable by assigning a value to a key in the $$\_$SESSION array, like this: $$\_$SESSION$[\text{'}$variable$\_$name'$]=$ 'variable$\_$value';

$4$: Create a second HTML form that allows the user to select and unset a specific session variable. The form should have a dropdown menu that lists all the session variables currently set. When the user selects a session variable from the dropdown menu and submits the form, the session variable should be unset using the unset$()$ function in PHP$.$ You can unset a session variable like this: unset$($$$\_$SESSION$[\text{'}$variable$\_$name'$])$;

Test your code and make sure it works as expected.