Make sure to take the following precautions before doing any change
1. Apply the where use list of that table/ Field and check whether it has been used in some program and FM or not. If yes then check one more thing that check the TYPE of another variables on which system has populating data (move, write or in FM parameters). if you will not consider this then you can land you in big trouble. (Conversion dump)
2. Ask the basis to take a dump of the production, quality and data for the safer side if something does not go right.
Now, you can do the changes in your development system and then adjust the database and see the impact of it.
Hopefully, you will not come across any difficult situation in this changes.