Is it a local install?
Whilst there is no current method to do this on par with the trim function, there is the post-process module that could possibly “remove spikes”.
Or if this is not an emonPi/emonBase (ie using buffered-write) and there are only a couple of errors, then you maybe able to edit those few points manually.
This best fix moving forward is too either sanitise the data using processes like “skip if over 80” or even better, stop the source of the data from posting obviously out of range data.
If you are only concerned about being able to see the valid data better, then a quick fix to view the data already contaminated with spikes could be to “fix” the vertical scale to say 80 or 100 degs so that your valid data is displayed at a better resolution and the invalid spikes are pushed off the top of the chart.
[edit]
In fact, if you are running the latest emoncms code. I think you can “block edit” or replace a block of values with nulls (effectively delete)
But be aware of some quirks I experienced prior to the latest changes, but I’ve not had time to confirm if those “quirks” were fixed or not. (Unearthed a quirk with editrealtimedata timestamps)