The best way to accomplish this with the current PicoScope 6 build is to apply a measured amount of resolution enhance to the channel you wish to filter. Be careful with this so as not to filter out things that may be important.
Watch for an even better method in the next build
There are also filtering options in PicoScope 5 but the filtering is not channel independent so affects all channels.
THE PicoScope Automotive Authority
In North America