How to customise Excel toolbars
To insert an icon in Excel, click on Tools > Customize > Commands. From the left-hand panel select the category of command. Choose the icon and drag it to the appropriate toolbar and then click on Close.
(a) In the case of inserting an 'Insert Row' icon, click on Tools > Customize > Commands. Then select Insert and then drag the Rows icon (the second in the list) to a chosen toolbar at the top of the screen. Then click on Close.
(b) In the case of inserting a 'Delete Row' icon, again click on Tools > Customize > Commands. Then select Edit and then drag the Delete Rows icon to a toolbar. Then click on Close.