Hey hi ***[link|https://www.ifixit.com/User/4532672/Chitranjandas|Chitran|new_window=true]***, power adapter heating problems are becoming quiet common now a days. The fix can be easy and sometimes not even feasible.
If you are using some case for your charger then just remove it while your charging your phone with it. It might cause problems with heat dispersion. Also ensure that your phone has the up to date firmware. Outdated software do lead to over heating. Check for your environment, is it too hot? If that's the case then the warming of the charger is very natural, but don't charge it for a very long time in such a environment. Give breaks to the charger or charge it time intervals. If your charger is a fast charger then again it is very natural for it cause overheating because fast chargers generally produce a lot of heat during the charging process. If your charger supports different speeds then try using the slowest one.
Thank you for reading and have a wonderful day =)