How many signatures does it take for a petition to remove any sitting president?

Zero. There is no provision in the US constitution for removing the president with a petition.

Only 285- but it has to be 218 members of the House of Representatives and 67 Senators.

You see, Presidents can't be removed by petition.  They can only be removed by impeachment, the end of the term of office to which they were elected, death, or resignation.

A sitting president can't be removed simply because you don't like him and/or you prefer someone else.  This isn't a popularity contest.  

No amount of signatures will suffice.  Presidents can only be removed by impeachment (which takes a majority vote in the House and a two-thirds majority in the Senate to convict).

A Petition will not remove a sitting President.  

More than 80 million this year and you can only petition on November 3rd. It's called voting though not petition.

For sake of argument we can say Trump was petitioned and was removed from the office of the the president of the United States, if that makes you feel better.

66.6666666667, and all of them have to be sitting Senators.

Only the House and Senate can remove the President. It is called impeachment. Where have you been for the last few years?

just yours because of how important you think you are

There isn't a mechanism for removing a president from office via a petition.