Yes, the 'fifth glyph' is the letter 'e'. "Ditching that fifth glyph" means writing without using the letter 'e'.
This is supposed to be a fun way for folks to 'prove' and 'verify' that they have a brain. (It takes some serious brainpower to write coherent prose and poetry without using the letter 'e', which happens to be the most-frequently-used letter in the English alphabet).
The fact that it's hard to do is why extra VYB will be given to folks who submit original content to Proof of Blind without using the letter 'e'.
NOTE: Some folks might be tempted to simply drop the letter 'e' and replace it with an apostrophe, as in "What th' h'll was I thinking?" Don't expect much extra VYB for just doing that. You'll need to look for synonyms and find other ways to structure your sentences, e.g. "What in tarnations was I thinking?"
Have some fun with it. Show your creativity.
Ok, cool. I get it completely now. Its surely fun and tasking. My only quarrel was that the whole concept wasn't explained, all I saw was 'ditching that Fifth glyph' and explanations that wouldn't dare use the Fifth glyph even when they were trying to explain the concept, so it was kinda hard to know what it was all about.
Okay, I'm the sort of guy that can boss around a challenge such as this. No more talking, I'll show you in a post.