rm sequence_1*.hmf
removes files beginning with sequence_1 and ending with .hmf.
Globbing is the process in which your shell takes a pattern and expands it into a list of filenames matching that pattern. Do not confuse it with regular expressions, which is different.
If you spend most of your time in bash, the Wooledge Wiki has a good page on globbing (pathname expansion). If you want maximum portability, you'll want to read the POSIX spec as well / instead.