If it is not programmatically then use
'Delete Face' command from 'Synchronous Modeling' group.
Either use command finder or from the menu bar, Insert > Synchronous Modeling > Delete Face.
Once 'Delete Face' dialog is active, you can use 'Connected Blend Faces' or 'All Blend Faces' from the selection filter as per your need.
In the .NET world, the things you need are NXOpen.Features.DeleteFaceBuilder, and NXOpen.Features.DeleteFace. The same objects/methods are available from C++; only the syntax is different.
Delete some blends interactively, and record a journal. The recorded code will probably be very long, but it will show you how to use the DeleteFace functions.
The attached should be a good start. You'll need to add the part that checks the radius.
It does this:
Pick a body.
Get all the features of the body.
For each feature, does the sysname include "Blend"? If so, put it on a list.
Starting with the most recent blend feature, delete them all, one at a time.
Update the model.