Regex can this be achieved
===

I'm too ambitious or is there a way do this

`to add a string` **if not present ?**

and 

`remove a the same string` **if present?**

Do all of this using Regex and avoid the if else statement

Here an example 

I have string 

`"admin,artist,location_manager,event_manager"`

so can the substring **location_manager** be added or removed with regards to above conditions

basically I'm looking to **avoid the if else statement** and do all of this plainly in regex

`"admin,artist,location_manager,event_manager".test(/some_regex/)` 

  The  some_regex will remove **location_manager** from the string if present else it will add it

 
Am I over over ambitions

