Legally, Here are a few things he can do...
He can purchase gifts with it (as long as it isn't "family"), He can use it on a future campaign or give it to another persons campaign, He can use it on people who worked on his campaign, or he can donate it to a charity.
Donating it to charity is pretty much known to be a money laundering scheme. They keep operating expenses and pass the rest on, round and round until it is all dolled out.
I replied to a tweet that a Bernie gal tweeted just yesterday.
She truly believed Bernie would win the presidency.
I told her he’d bail on her and the rest of the Bernie Bros just as soon as he got enough $$$ or someone offers him another lake house.
Bernie Bros continue to allow the old comrade conjob to con them.
Those who label words as violence do so with the sole purpose of justifying violence against words.