Kırmızı notalar

You're in an English forum.

Google Translate:
When the notes turn into another instrument, what do the red notes in the middle mean and what should be removed (invisible) and how to do it?
Thank you

Probable answer (because the question isn't fully clear when translated this way):
MuseScore displays notes that are considered outside of the professional range for an instrument in red. This only affects the display color in the program; when exporting/printing your score, those notes will be black.
The solution is to likely rewrite/transpose that part of the melody to make it fall into the playable range of the new instrument.

Kırmızı notalar, Estrüman'ın çalma alanı dışında olduklarını gösteriyorlar. (bir uyarı olarak)
The red notes indicate that these notes are outside of the Instrument's range. (as a warning)

Resimde gösterilen yerdeki işareti kaldırın.
Turn off the tick (located in the field, with the red square marked).