how to delete these undesirable things

Can you help me…i thought i would do this in ten minutes but now after one hour I can’t understand
don’t see any information when i selecte these objects:
How to delete it, alpha to 0, size to 0 ???
best regards and thanks

In the Kit Editor, put all your instruments in the same voice, with the stems pointing in the same directions. Then, in the score, when you want stems pointing in the opposite direction select the notes and hit F (for flip).

Alternatively, use the notation option to consolidate drum kit instruments to a single voice.

There’s no easy way or hiding rests in kits; you have to ensure that Dorico doesn’t create the rests in the first place.

For the bracketed number [1], that’s the bar number - you can hide that in Setup>Layout Options>Bar Numbers.

thanks to both for taking your time to allow me to save some