Use this procedure to clear the statistics for each collector.
You must globally enable sFlow.
enable
clear sflow statistics [collector <1–2>]
show sflow statistics [collector <1–2>]
Clear the statistics for collector ID 1.
Switch:1>enable
Switch:1#clear sflow statistics collector 1
Switch:1#show sflow statistics collector 1
==================================================================
                             sFlow Statistics Info
==================================================================
Collector-id                  sFlow-Datagrams
------------------------------------------------------------------
1                             0
------------------------------------------------------------------
All 1 out of 1 Total Num of sflow statistics entries displayed