This might work for you:
finger | sed 's/\(.\{35\}\)...../\1/'
or this:
finger | cut --complement -c36-40
This solution is not perfect: the column position and width might change. If they are constant, the following command will do the trick by removing text columns 34 to 39 inclusively:
finger | colrm 34 39
If "\t" is used as column delimiter then you can get rid of 4th column using awk and delete doubled "\t" using sed. For example:
"\t"
awk
sed
finger | awk -F"\t" -v 'OFS=\t' '{ $4=""; print $0}' | sed 's/\t\{2,\}/\t/'