Best way to remove a 2yr old PAID collection from report

[Michael Bridges]

I have 2 collection agency listings on my credit report that I wohld obviously like to remove from my credit report to help with my real estate investing. Both of them (MCM and EAF) are about 2 years old and both are paid. Has anybody had any luck in this area, and if so, how did you do it? Goodwill letter? Challenge letter to creditor? Challenge letter to credit bureau? Thanks!