I think that there should be a button to completely reset your Trading Inventory and DP, but you keep Credits and rank colors/tags.
For the inv reset, just throw everything in the bin. And as of yet I can’t find a use to DP, so you don’t need to worry a lot about that.
I don’t understand the practicality of resetting your inventory storage space (I’m guessing rank colors/tags is referring to the equip slots?) and your DP. DP is the virtual currency. At this time, items are mainly used as a currency because DP itself has no further use (ignoring XP Efficiency update). And the fact that trading with DP is a little more difficult (DP in trades will be added). In the future there will be a multi-delete tool for simply clicking on the items you want to delete rather than picking them up and throwing them in the bin (which gets tedious with a big inventory).
However, selling the items in V0.7 will be much more cost effective and is recommended because the system was built to give you more ‘DP’ (in the sense of items) as long as you sold said items and didn’t trash them.