Google Glass makes it very easy for Glassware apps to 'liter' the timeline (especially with news items). Is there any easy way to clean/delete items you don't want?
Many of these items cannot be deleted, and the apps themselves (like Winkfeed for example) don't seem to have that feature. I know your OWN apps can delete their own items, but haven't found a way to delete/manage ALL the items on my timeline (including those created by other apps).
If you're developing a Glassware
You can use the Mirror API's delete method or tools like Glass Cleaner to clear up timeline items.
If you're a user of a Glassware
The management of the timeline items is up to the developer of the Glassware. There's no way to override this from Glass, but your timeline isn't infinite. They'll fall off the timeline after about 7 days, or when your timeline exceeds about 200 items.
In general, the design philosophy for Glass is to discourage you from managing your timeline like an email inbox. By design it discourages you from achieving timeline zero. The intent is to avoid using it like a fire hose that you try to manage, but instead to think of it like a stream that you dip your toe into now and then.