This is not recommended as you might be missing important information about why your messages are not being delivered. Knowing this info allows you the chance to correct these issues and possibly save you credits next time. For a list of what costs credits, and what doesn't, check out this article HERE.
For a list of possible undelivered message reasons, click HERE.
If you are sure you want to proceed and clear all your undelivered message alerts (mark them as read):
1. In the HUB, Click the filter icon.
2. Expand the options under the" Undelivered" messages filter and select "unread/read" to show those unread, undelivered notification messages.
3. Then you can click "Clear", and select "Yes, clear" to mark those as read.