There are numerous scams out there so it's important to do your research.  It's very rare for any company to remove the activation lock for free—if you see such claims, those are likely scams. If you're unsure of a company, check for reviews at RipoffReport, TrustPilot, or Trustmark Reviews. Some recommended pay sites are iPhoneIMEI.net and Official iPhone Unlock. The unlocking service needs this code to unlock the phone. Here's where to find it on different models:   iPhone 6s, 6s Plus, 7, 7 Plus, 8, 8 Plus, iPhone X: You'll find the IMEI on the SIM tray. Insert the SIM ejection tool (or the end of a paperclip) into the hole on the tray, which is located on the right side of the phone. Pull out the tray and find the IMEI on the tray's outer edge.   iPhone 5, 5c, 5s, SE, 6, 6 Plus, iPad: The IMEI is printed on the back of your phone toward the bottom. The number is prefaced by “IMEI.” Enter the IMEI, model number, and payment information as requested by the site, then follow the on-screen instructions to complete the unlocking.

Summary:
Search the web for a reputable iCloud lock removal service. Get your iPhone's IMEI code. Follow the instructions on the site you selected.