You invoices and estimates use items / service / products that your sell.
You can create and update those for future use.
Adding new items from an invoice / estimate
Within an invoice or estimate you can click "Add item"
Click inside the "Item name" field.
Your list of items will drop down and allow you to search for the right one.
If an item can not be found you'll see a green "Create new" button.
Once clicked, you'll be able to fill out all the items details and use it in your invoice.
Now, you can use this item in all future jobs/ invoices / estimates
Updating an item's details
You can easily manage your items by going to "Settings" -> "Items & products"
Here you can find your items list and make changes such as changing the price or description.
After saving all future invoices using this item will reflect your changes.
Removing an item
With Workiz you can't really delete an item, you can however disable it.
Go to "Settings" -> "Items & products"
Next, edit the item you wish to disable.
Switch the status to "disabled" and save.
Now this item will no longer be suggested in your invoices.