After editing a single still in lr from a folder in lr I go to File>export to make a shareable jpeg to put on Desktop,for example lrtimelapse box comes up which I dont want.So how to export a still shot in lroom avoiding the lrtimelapse box appearing? thnk

Just switch to another preset on the left in the export dialog. That's how Lightroom works ;-)
It always shows the export preset you used last, if you want to export stills, choose another preset.