To move a coin/asset from one portfolio to another is fast and easy!
Go into the portfolio of the asset you want to move and then click on that asset.
Tap on the three dots in the top right.
Press Move to another portfolio.
Select the portfolio you want to move the asset to and voila!
PRO TIP: Moving an asset moves all transactions as well as any linked transactions with it. Therefore if you have "deduct from..." or "add to..." options turned on, it will move those secondary transactions from other assets as well!
For example, if you move LTC and there is a buy transaction of LTC/ETH with "deduct from ETH holdings" enabled then, the sell transaction automatically created under Ethereum will also move with LTC. This may mess up your ETH holdings so please check this beforehand. If you proceed, you can add in a manual transaction to correct your ETH balance in the original portfolio.
PRO TIP 2: Once you move a coin to another portfolio, the action is irreversible if the other portfolio already has some transactions of the same coin.
For example, if you move LTC from Portfolio A to B and Portfolio B already has some LTC transactions then transactions from Portfolio A will be merged into those of Portfolio B and there will be no way to separate these later.
PRO TIP 3: It might take some time to move over the transactions if there are a lot of them. Please close Delta, wait a minute or two and reopen Delta and the transactions should have moved over successfully.