How to 'drop'/delete characters from in front of a string?

Just using bash (or ksh93 where that syntax comes from or zsh):

string="H08W2345678"

echo "${string:3}"
W2345678

echo "${string:0:-4}"
H08W234

See the Wooledge wiki for more on string manipulation.

$ echo "H08W2345678" | sed 's/^.\{3\}//'
W2345678

sed 's/^.\{3\}//' will find the first three characters by ^.\{3\} and replace with blank. Here ^. will match any character at the start of the string (^ indicates the start of the string) and \{3\} will match the the previous pattern exactly 3 times. So, ^.\{3\} will match the first three characters.

$ echo "H08W2345678" | sed 's/.\{4\}$//'
H08W234

Similarly, sed 's/.\{4\}$//' will replace the last four characters with blank ($ indicates the end of the string).

How to 'drop'/delete characters from in front of a string?

I have a string that I would like to manipulate. The string is H08W2345678 how would I be able to manipulate it so the output is just W2345678?

echo "H08W2345678" | cut -c 4-

Similarly if the I wanted to drop the last 4 characters from H08W2345678 so that I get H08W234 how would I do this?

echo "H08W2345678" | cut -c -7