根据选择更改删除字段

Basically I'm not a coder I need an example of the proper code to accomplish this please. I am trying to make an electronic PTO form which I have linked within fiddle. What I want to do is if type1 changes then it deletes or subtracts anything in hours1 and really preferably in what ever total field the type1 has filled. So if you go to fiddle select Sick and type 8 in the hours field it will auto count in the total hours for sick onchange. However what if someone selects sick and really meant to select vacation currently they have to manually delete and re-enter all the numbers. I would like to automate the whole thing. I really appreciate your wisdom on this.Basically I'm not a coder I need an example of