[flotzam]

It's exposed in Electrum and the Bitcoin Core GUI wallet. Perfect for donations, you can spend one UTXO without change.

[kragen]

Where is the option in these UIs? I currently use Electrum mostly but may switch back to Bitcoin Core.

[flotzam]

Electrum: View > Show Coins (adds a new Coins tab)

Bitcoin Core: Settings > Options... > Wallet > Enable coin control features (adds it on the Send tab)

[kragen]

Thank you!

[redox99]

Coins tab, right click on the coin, spend.