how to delete tracks of SFF1 styles before loading them in PSR-E373

[dogendo]

Hello

I have a PSR-E373 which I am very happy with.

But I used to play on previous keyboards muting styles tracks, keeping only Bass+Drums of the automatic accompaniments.
As it is not possible to mute individual style tracks with PSR-E373, I plan to load 10 styles previously modified on my PC (deleting useless tracks and  keeping only  drums and bass tracks). Which software should I use ? With Styles-revoicer from Jososoft I can't delete styles tracks but only set volume to 0. Is there another way to do it ?

And by the way is there a source to download free styles compatible with  for the PSR-E line ?

Thanks for your reply

Michel