Readonly Grid, Delete functionality

There are 2 ways of doing it and you can decide based on your requirement. 

1. Store all the selected row's identifiers in a variable and then use a!deleteRecords directly from the interface in a dynamicLink's saveInto. 
2. Store all the selected row's identifiers in a variable and then start a process on dynamicLink's saveInto in which you call the same smart service.

Now if you want to generate the memory footprint and so some more operations in addition to deleting the data, you can use the second option or else first option should be fine. 

I am trying with the option-1, but I did not find a!deleteRecords.

I am using version 21.4, I am not sure a!deleteRecords is available after 21.4 version.

you can use a!deleteFromDataStoreEntity 

a!deleteRecords() function was introduced in 22.3 version. In your case, you can use  a!deleteFromDataStoreEntity() function.

a!deleteRecords() function was introduced in 22.3 version. In your case, you can use  a!deleteFromDataStoreEntity() function.