The XRP Ledger protocol requires that each XRP Ledger wallet holds a small amount of XRP at all times. This is called a reserve and its purpose is spam protection (more details about XRP reserve available here).
The main reserve requirements are:
- 20 XRP per address (always required - cannot be withdrawn)
- 5 XRP per each trust line (until disabled)
Trust lines can be disabled in order to make additional XRP available. How to disable a trust line?
- 5 XRP per each open order (until executed or cancelled)
- A wallet has an XRP balance of 50 XRP
- It has ETH and EUR trust lines enabled
- It has one open order
Available balance is:
50 XRP - 20 XRP (base reserve) - 2 x 5 XRP (trust line reserve) - 5 XRP (open order) = 15 XRP
XRP Ledger wallet balances cannot be consolidated. Each active XRP Ledger wallet must hold at least 20 XRP. "Once created, an account exists in the XRP Ledger's data tree forever." More information available here.
Deleting an XRP Ledger wallet from your GateHub account will not make the 20 XRP reserve available.
In "EXCHANGE", the reserve is automatically set to 50 XRP as a security feature and only occurs if you click on "All available". If you input the numbers manually, you can exchange to the minimum available XRP balance.