The forward animation keys, will normally be found in the Hip of the figure,.
You can either de-select the Hip bone from the NLA Track “parameters”, which control what parts of the figure the Clips in that track will animate.
Select the NLA Track,. Go to the NLA tab on the right and click parameters,. then select / de-select from the list of bones. (pic)
You can load in the Clip data into the sequencer time-line,. as key-frames,. then edit the Hip animation tracks,. Expand it to see the “position” Y track, and delete the forward motion keys, except the first key, ..which needs to be there.
Save that animation as a new clip
Hope it helps
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