Summary:
We are selectively tiering some users up as we work to expand capacity. These upgrades are on a case by case basis. Please note that we do not evaluate accounts for tiers or provide tier upgrade assistance through the forums or through merch-sellers-contactus@amazon.com.
We are working hard to expand capacity at this time and we will post an update to the Merch portal dashboard when we resume reviewing all accounts for tier upgrades.
To make new spots available you can delete shirts you no longer wish to sell under the "Manage" tab. Any shirts you delete will be subtracted from your total live t-shirt count in your tier once the deletion process completes. Please note, this can take several hours to process.
For more information, please see the following article:
https://forums.developer.amazon.com/articles/20079/how-do-i-edit-or-delete-a-live-shirt.html