Insert Tab
- Select the element on which you are going to apply Subscript.
- Then go to Insert Tab.
- And then select Special Character option.

Format Tab
- Select the element which will be Subscript
- Then go to Format Tab
- And click on Text after that select the Subscript.

Key Combination
As usual select the element which will be Subscript then press CTRL +,
To remove subscript press CTRL +, again.
To use Superscript in google docs, follow the same process but when you use Key Combination then press CTRL +.
Equation
To use the equation editor, open a Google Docs document. In the document, select the Insert menu and select Equation. This opens the equation editor.

Edit and Delete an Equation
Once we have inserted the equation, it appears in the document as an image. To edit or delete it, you just have to click on it with the mouse to select it and the labels to edit or delete appear. As it is an image, we can also pull the corners to increase or reduce its size. The document can be exported to other formats such as Word or Open Office but the equation cannot be edited outside of Google Docs.