There have been no printed cards that remove static abilities without also setting the power and toughness (Snakeform, Ovinize) or changing the card to no longer be a creature (Soul Sculptor) as stated in ghoppe's answer.
Tarmogoyf's ability which sets its power and toughness is in a special class of static abilities called
characteristic-defining abilities [CR 604.3] which function in all zones and even outside of the game. Any hypothetical card which exclusively removed static abilities would need a special ruling on its interaction with these type of abilities.
* representing power and/or toughness are treated as 0 (even within calculations) in the case of static abilities that create replacement effects [208.2b] and also characteristic defining abilities when the value of the asterisk cannot be determined.
In addition to these definitions, Gatherer also treats asterisks as zeros with constants added continuing to be added. To find Tarmogoyf in Gatherer by Power and Toughness alone, one must set the search parameters to Power=0 and Toughness=1.
It is reasonable to assume that any future ruling would be consistent with this and set completely undefined asterisks to zero, although this is just speculation on my part.
If we assume that the above proves true then we can make the following conclusions regarding the specific creatures mentioned in the question.
- If Tarmogoyf somehow lost his ability which defines the value of
* would be taken as equal to 0 so that it would become
0 / 1+0 => 0/1.
- Boneyard Wurm would become a 0/0 and thus under
[CR 704.5f], be put
into its owners graveyard. (Of course, once in the graveyard its power and toughness would be reset based on its characteristic-defining ability)
The rulings for Nightmare help clarify some of the interactions with asterisks in power/toughness.
If you control 0 swamps, then the Nightmare has 0 toughness and will be put into its owner's graveyard as a state-based action right before the next player gains priority.
Nightmare's power and toughness changes as the number of Swamps you control changes.
The ability that defines Nightmare’s power and toughness works everywhere, not just on the battlefield.
[CR 208.2a] in reference to Asterisks in Power and Toughness
This ability functions everywhere, even outside the game. If the ability needs to use a number that can’t be determined, including inside a calculation, use 0 instead of that number.
Example: Lost Order of Jarkeld has power and toughness each equal to 1+*. It has the abilities “As Lost Order of Jarkeld enters the battlefield, choose an opponent” and “Lost Order of Jarkeld’s power and toughness are each equal to 1 plus the number of creatures the chosen player controls.” While Lost Order of Jarkeld isn’t on the battlefield, there won’t be a chosen player. Its power and toughness will each be equal to 1 plus 0, so it’s 1/1.