Page 532 - Bob Holtzman "The Field Guide to Knots How to Identify, Tie, and Untie Over 80 Essential Knots for Outdoor Pursuits"

2. Pass the rest of the sling through the bight and pull it tight.

Untying: If both working ends are free, simply grab the crossing part and
pull. If only one working end is free, pull on the turn in the standing part to

draw the free working end through the crossing part. If both ends are to
remain tied, pull some slack into the standing parts, then pull the slack into

the crossing part: the knot can then be slid over the end of the fixed object.

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