You can change CVs in a Marklin decoder using a Lokprogrammer, but you cannot load sound files into the decoder. For that you will need a Marklin programmer.

The Lokprogrammer is required to load sound files in a Loksound decoder.

But I don't understand what you are attempting to do when you say 'erase values'. I think you need to explain what you want to do a bit further.

No, you will need a Marklin programmer. But I am not sure if you can write over an OEM factory fitted decoder. You can certainly update the firmware, but I am not certain if you can overwrite the sound file. You may need to replace the decoder to do that.

On several newer mfx+ locomotives, you can overwrite an OEM factory-fitted decoder using a CS3/2 and a PC. It is currently not possible to use the Marklin USB programmer. (as far as I know).

It is possible as long as these three conditions are in place:
1. Decoder firmware must be above 3.2.x.x, or it must be possible to upgrade the firmware. If the decoder has a firmware version below 3.0 it's not possible, and Marklin started to use v3 firmware around 2015/16, there was probably some overlap also.
2. Marklin must have released the original decoder project for that exact model. you can not even use a product number below or above. The original decoders only respond to the original projects, probably because of an encrypted code.
3. you must have a CS3/2 and have it connected to a pc with the Marklin mDecoderTool software. and program the locomotive "through" the CS2/3. (takes around 50 minutes). The locomotive must be on the program track.

If these conditions are met you can almost do whatever you want as long as you start out with the original project. You can even replace the running sound. Note that some early v3 decoders are only 32MBit, (no warnings given) and you must make sure you stay within that size limit.

and, if you want to adjust engine volumes like normal load, unloaded (leerfall) and steam hiss (underlying steam sound, Grundrauschen), you have to upload the entire project to the decoder.

so far I have done this on several locomotives including the new: 02, 06, 78.10, 844, E991, SNCB class 1, etc. one thing I often do, is adjust some sound levels to my liking and replace the german locomotive info sound files with something more interesting. I also often replace some of the standard sounds with some actual sounds if there are better actual sounds available from other sources.

In fact, Marklin has also released upgraded sound projects for some locomotives. E.g when Marklin released the 37997 big boy it was released with an "old" running sound. later Märklin silently released an improved sound project. and those with a 37997 and old project should be able to upgrade. but if you have a 37996 you can not upgrade because Marklin has not released a decoder project and the decoder is probably also too old. (the first version of the 37997 project is 7.32 MB and the new version is 13.1 MB.). note that I don't have the 37997 myself, but this is mentioned on other forums and there are some youtube videos also. I noticed this when I upgraded my old 37990.

And of course, if you try this, it's at your own risk. and this post is not intended to be complete instructions. just information on what's possible etc.

Great info, Thank you!