Apply initial filter based on other field value

I have a field which lists all Accounts, and have a filter to choose only parent accounts.

Here I have a drop down field in which if I choose one option then only I need to apply the initial filter on the Account field. If I choose other drop down values, the filter should not apply.

For example,

if (dropdown value == 1){

   apply the filter on Account field;   

}

else{

   dont apply the filter;

}

How can I achieve this.