if you don't want to see the sum as it is calculated then change the last somavalor to "", this will hide the sum.
Depends on where you want to see the total. At the end, just write another formula:
Numbervar somavalor
and place this where you want it. If it to be anywhere except the bottom of the report, you will need to create subreport to calc this number first.
Since Crystal reads the data one line at a time, with this type of formula, you need to read all the data first, there is no Aggregate that will work.
HTH