You can trim the results in the Custom dashboards by going to the chart containing the results you want to trim and selecting Edit chart > Trim:
The results can be trimmed by using five conditions:
Top N: limit the number of results on the chart.
Non zero: this option excludes data if the result is 0
Allowed: includes only parameters entered (in this example, positive and negative sentiment).
Rejected: excludes entered parameters (in this example, positive and negative sentiment).
Merge other: you can define the rank (after which the data will no longer appear) or percentage (below which the data will no longer appear).