Hi rshah,
You can clean the data up by exporting it using the download arrow in the image you shared, then using the add/modify/delete column to specify you wish to delete those values, then you can use the /dataImport.shtm page to have those changes processed.
Then, on the data point itself, you can use the "Discard extreme values" settings to avoid having extreme values in the data to begin with.
Edit: Yes it would be possible to review existing values and clean them from a script. I think it would look a lot like this....
//Untested
var toDelete = [];
var pntId = 1;
var pvd = com.serotonin.m2m2.Common.databaseProxy.newPointValueDao();
//Do the query
pvd.getPointValuesBetween(pntId, 0, new Date().getTime(), function(item, index) {
//Find the values to delete in the callback
if(item.value > 123) toDelete.push(item);
});
for(var k =0; k < toDelete.length; k+=1) {
pvd.deletePointValuesBetween(pntId, toDelete[k].time, toDelete[k].time+1)
}