Hi Amanda, I presume when you say line items you are actually referring to list items (i.e. records)?
This can be facilitated by creating a boolean line item and creating a formula that sets the boolean to true if the year is equal FY19. Remember that best practice is to create a SYS module where you define the parameters (FY19) rather than hard coding with the formula. Once you have your boolean line configured, within the Actions tab create a a new action to Delete from List using Selection and reference the boolean line item in the "Selected using" field. Below is a helpful article on this topic.
If you are wanting to remove all data from any month in FY19 from the model and you are using native Time, can you just adjust the Time Range or model calendar to remove the FY19 year. But remember, this would be for the entire model, is that what you are wanting to do?
Conversely, in rereading your post, do you have actual line items that have the name or format as FY19? Maybe a picture would be helpful to understand exactly what you are wanting to do.
I see different people interpreted your question differently. I actually have the same understanding as Rob. So yes; you can change the Time setting IF you want to remove FY19 from the whole model. If your ask is to remove the FY19 from this one module but leave it for other modules, then create a Time Range (from the Time Setting section) that does not include FY19, for example it starts from FY20, then use this newly created Time Range as the time dimension for the module where you want to remove the FY19 data
Einas "Give a Man a Fish, and You Feed Him for a Day. Teach a Man To Fish, and You Feed Him for a Lifetime"