I start regex search by C-M-s.
After typing in some pattern, I would like to edit the pattern shown in the bottom bar. But it seems that I can only append new characters at the current pattern, but I can't figure out how to erase the current pattern, (every time hitting backspace key will erase the text in the buffer window not in the bottom bar).
How shall I edit the search regex pattern?
How shall I start over the search i.e. without previous entered regex pattern?