Hi there, I can see that there is already a topic about this on the forum, however after reading it I am still confused. I am trying to export a trial version of my font with only a few basic glyphs rather than all of them. I have tried deleting all the glyphs I don’t want in the trial version and exporting, however I receive an error message stating ‘Error: “Glyph “acutecomb” not in font.” in Feature ccmp in line: 2’. In the other post it states I should ‘use a project document, link to your .glyphs file and add ‘Keep Glyphs’ and ‘Remove Feature’ parameter’. I’m unsure of what this means would you mind explaining how I can do this? thanks so much 
When you remove glyphs, you also need to remove OpenType feature code that references those glyphs. If you have written those features yourself, you need to edit them manually. It you let Glyphs write the features, you just need to press the Update-button in Font Info > Features.
I would recommend to add a second set of instances (in Font Info > Exports) with a different name and a Remove Glyphs or Keep Glyphs parameter. Then you can export the full font and the trial font at the same time without disturbing your main source file.
Perfect! Thank you for your advice, Its very helpful.