In answer to your question, try here for drivers
http://www.dell.com/support/home/us/en/19/Drivers/DriversDetails?driverId=R11443 6
(from 2011)
as for uninstalling the Dell 1255 MP installlation, after you have done installing it, the original file should be on your desktop as XX.zip, drag it to the trash, and empty trash. If you want to get rid of the files themselves, go to system preferences, then printing click on the printer icon you want to remove , and click on the Minus key and it should go bye-bye. The files themselves should be found under yourname, double click on that, then go to top of screen and choose Go To, and in the box that appears there, type in Library and click on OK. You should be able to find Printers from there. Or you could try going to Hard Drive, then Library, then go to Printers and the files should be there. According to dell, the 3115 or 3130 are compatible with el Capitan. so you could give 'em a try rather than the other driver.....your mileage may vary, though
John b