Remove first three occurrences of space

Question

I need to remove the first three occurrences of space per line in a text file.

I have tried the following:

sed 's/ //3'

This only removes the third occurrence.

sed 's/ //3g'

This leaves the first three occurrences of space alone and removes all of the following, this is the exactly the opposite of what i want.

Answer 1

sed -e 's/ //' -e 's/ //' -e 's/ //'

Answer 2

sed 's/ \{1,3\}//' < file.txt