How to Freeze Boiled Sliced or Diced Sweet Potatoes - https://www.thespruce.com/how-to-freeze-sweet-potatoes-three-ways-3061558
Bring a large pot of water to a boil. Scrub the sweet potatoes and put them in the boiling water.
Boil for about 10 to 15 minutes, until they just begin to be tender but are still quite firm.
Remove the sweet potatoes and let them stand at room temperature until cooled.
When cool enough to handle, peel and slice or dice.
Put the sweet potatoes in freezer storage bags. Remove as much of the air from the bags as possible. Freeze for up to 12 months.
How to Freeze Baked or Mashed Sweet Potatoes
Heat the oven to 375 F. Place a large baking pan or foil on the bottom rack of the oven.
Scrub the sweet potatoes, poke them in a few places with a fork, and place on the rack in the oven.
Bake the sweet potatoes for about 45 mins. to 1 1/2 hours (depending on size), or until tender. Let the potatoes cool for about an hour in the oven. At this point, you can wrap the cooled sweet potatoes in foil and transfer them to freezer bags to freeze whole.
For mashed, take the cooled sweet potatoes out of the oven, slip the skins off, and put the flesh in a large bowl.
Beat the sweet potatoes until smooth. You can add a tablespoon of lemon juice for each 1 pint of sweet potatoes if you wish. Lemon juice helps prevent browning, but it isn't necessary.
Pack the sweet potato mixture into bags; flatten the bag to remove as much air out as possible. Freeze the sweet potatoes for up to 12 months.
To reheat whole baked sweet potatoes, remove the foil. Rewrap them in a new sheet of foil and bake in a 350 F oven for about 25 to 35 minutes.