or textures might makes sense when you have a small computer like RaspberryPi. For a normal computer it is useless and has no benefit.
If you want to delete charts of the cm93 bundle which you don't need you have to know how cm93 is organized. There are about 144 subfolders in a cm93 folder which are named as numbers.
The system for c-map
is very simple. All folders contain segments of 20 x 20 degrees.
00300000 means 80S 0E, 00300060 means 80S 20E, 00900120 means 60S 40E. The first 4 digits is south to north 0150=40S +20 north, 0210=20S, 0270=0S (equator and 20 degrees north), 0330=20N, 0390=40N. The last 4 digits is East from 0 meridian.. 0060=20E, 0120=40E, 0180=60E, 0240=80E, and so on 0480=160E, 0540=180W, 0600=160W and so on..
The folders in the next level is a - z, where z is scale 40x40 degrees,
a is20x20 degrees, b is 10x10 degrees, down to f and g which is scale of
20x20 arcminutes, which is harbour level.
Using this explanation you are able to delete the charts you don't want to keep.