Frankly speaking, deleting ringtones is not an easy task.
Usually, this task is managed through iTunes. The .m4r files are stored under the "Tones" section. However, ringtones pushed to the device with a third-party app (like WALTR 2) are not getting displayed in Tones through iTunes.
Ringtones do not require much storage on the device. Nevertheless, having tones of unneeded ringtones can be irritating.
In this case, we suggest you use the iRingg app as a tool, that can let the user manage media files on the iPhone. Please find more information via the link -> https://softorino.com/iringg/
IMPORTANT: You will have to install iTunes to use this app. Make sure to download iTunes from the Apple website and not from Microsoft Store.
Let us know if any questions may arise during the deleting procedure.