Ulbricht is the creator of Silk Road, a now-defunct criminal marketplace that used bitcoin to facilitate the sale of drugs and other illegal goods.
Silk Road was hacked, and someone got off with 69,370 BTC before the marketplace was shut down. Ulbricht was sentenced to life in jail without the possibility of parole in 2015, after the marketplace was shut down, and was compelled to pay $183 million in reparations related to Silk Road's total sales.
In November 2020, the government seized the hacker's 69,370 BTC. Ulbricht surrendered whatever rights he had to the bitcoin in this court petition, which was made in February 2021, and is now using it to settle his obligation to the government.
According to the filing:
“Ulbricht further relinquishes all right, title, and interest in the [69,370 BTC] and agrees that said property shall be forfeited to the United States and disposed of according to law by the United States. [...] The parties agree that the net process realized from the sale of the Subject Property forfeited pursuant to this agreement shall be credited toward any unpaid balance of the Money Judgment,” where the ‘Money Judgment’ is the $183 million Ulbricht owed the government in relation to his participation with Silk Road.
The "disposal" of surplus bitcoin might resemble GSA auctions, in which forfeited currency was auctioned off in lots to willing bidders.