How to delete system file in Mac OS Catalina 10.15.3?
I would boot to Recovery HD and use terminal (it is in the Utility menu) to remove the files you want to delete. SIP doesn’t need to be disabled on your system, just use a different system to do the delete and then restart back in the now modified system. 

Keep in mind, deleting the file is easy to understand and execute. Making persistent changes (across updates or if Apple recreated the file you chose to delete) or effecting 
permission changes is significantly harder on Catalina due to the system / data split. 


Catalina not allowing to change read/write permissions despite having SIP disabled