How to delete document from SharePoint by using Appian

Take a look here: https://learn.microsoft.com/en-us/sharepoint/dev/sp-add-ins/working-with-folders-and-files-with-rest

I hope, it might help you https://learn.microsoft.com/en-us/graph/api/driveitem-delete?view=graph-rest-1.0&tabs=http

DELETE /drives/{drive-id}/items/{item-id}
DELETE /groups/{group-id}/drive/items/{item-id}
DELETE /me/drive/items/{item-id}
DELETE /sites/{siteId}/drive/items/{itemId}
DELETE /users/{userId}/drive/items/{itemId}