How the python array gets the index based on the value, how to delete the value based on the index, and how to delete the value based on the value

Suppose there is an array of s = [1,2,3,4,5,6,7,8,9]

(1) How to get the index according to the value, if the value is 5, then the corresponding index is?

(2) How to delete the value according to the index, delete the corresponding value of index 5 in the array;

(3) It is easier to remove the values from the array.

Game over!

How the python array gets the index based on the value, how to delete the value based on the index, and how to delete the value based on the value