I'm selling / donating a lot of my inventory. Is there a more efficient way to remove them from Deckbox than going to each individual card and updating it?

Can I do something similar to adding from a list (I'm not opposed to typing in all the card names and quantities) and just using negative quantities?

Thanks.

If there's no better way of doing it, you can export your collection as a csv, wipe the collection on deckbox, edit the csv as much as you like and reimport. (keep a backup!)

There's unfortunately no good way to remove en masse on the website. The best way I know of is to edit your inventory's CSV in something like Excel.

1. Go to Inventory > Tools > Export. Make a copy of the exported CSV to serve as a backup in case anything goes wrong.
2. (Optional) For simplicity's sake, remove any columns you don't need, like My Price, Textless, Promo, etc. If you're not sure if any of your cards use these columns, then you can use Excel's Filter tool to see if the columns contain any values other than blanks. For instance, I use Signed, Altered Art, and Misprint, but none of the others, nor do I use Tradelist or Condition, so I end up with 9 columns.
3. In an empty column, type in whatever quantity you're getting rid of. Leave it blank if you're keeping all copies.
4. In row 2 of the next empty column, enter this formula: =A2-J2 where J2 is replaced with whatever column letter you were using in step 3.
5. Copy the formula down for your whole inventory. (There's multiple ways to do this, but I didn't want to assume any Excel ignorance by listing them. Feel free to ask if you need any assistance with using Excel.)
6. Copy the column from steps 4-5, and paste the values into column A (the Count column). Make sure it still has "Count" in the header row.
7. Delete everything from the two columns you were using in steps 3-5, save the CSV, and replace your current inventory on Deckbox with this CSV. You'll have to go to Tools > Remove Everything before importing, or else the CSV will just increase your counts, instead of replacing them.

Thanks for the idea! I've done CSV importing before with Deckbox but it totally slipped my mind here. Thanks all!