remove 'Delete emails from server' experiment

the function is superseded by 'Auto-delete messages'

DcCore/DcCore/DC/Wrapper.swift

@@ -340,10 +340,6 @@ public class DcContext {
         return Int(dc_estimate_deletion_cnt(contextPointer, fromServer ? 1 : 0, Int64(timeout)))
     }
 
-    public func emptyServer(flags: Int) {
-        dc_empty_server(contextPointer, UInt32(flags))
-    }
-
     public func isConfigured() -> Bool {
         return dc_is_configured(contextPointer) != 0
     }

deltachat-ios/Controller/AccountSetupController.swift

@@ -25,9 +25,8 @@ class AccountSetupController: UITableViewController, ProgressAlertHandler {
     private let tagSmtpPasswordCell = 10
     private let tagSmtpSecurityCell = 11
     private let tagCertCheckCell = 12
-    private let tagEmptyServerCell = 13
-    private let tagDeleteAccountCell = 14
-    private let tagRestoreCell = 15
+    private let tagDeleteAccountCell = 13
+    private let tagRestoreCell = 14
 
     private let tagTextFieldEmail = 100
     private let tagTextFieldPassword = 200
@@ -62,7 +61,7 @@ class AccountSetupController: UITableViewController, ProgressAlertHandler {
         certCheckCell
     ]
     private lazy var folderCells: [UITableViewCell] = [inboxWatchCell, sentboxWatchCell, mvboxWatchCell, sendCopyToSelfCell, mvboxMoveCell]
-    private lazy var dangerCells: [UITableViewCell] = [emptyServerCell, deleteAccountCell]
+    private lazy var dangerCells: [UITableViewCell] = [deleteAccountCell]
     private let editView: Bool
     private var advancedSectionShowing: Bool = false
     private var providerInfoShowing: Bool = false
@@ -111,14 +110,6 @@ class AccountSetupController: UITableViewController, ProgressAlertHandler {
         return cell
     }()
 
-    private lazy var emptyServerCell: ActionCell = {
-        let cell = ActionCell(frame: .zero)
-        cell.actionTitle = String.localized("pref_empty_server_title")
-        cell.actionColor = UIColor.red
-        cell.tag = tagEmptyServerCell
-        return cell
-    }()
-
     private lazy var deleteAccountCell: ActionCell = {
         let cell = ActionCell(frame: .zero)
         cell.actionTitle = String.localized("delete_account")
@@ -475,8 +466,6 @@ class AccountSetupController: UITableViewController, ProgressAlertHandler {
         case tagRestoreCell:
             tableView.reloadData() // otherwise the disclosureIndicator may stay selected
             restoreBackup()
-        case tagEmptyServerCell:
-            emptyServer()
         case tagDeleteAccountCell:
             deleteAccount()
         case tagAdvancedCell:
@@ -753,30 +742,6 @@ class AccountSetupController: UITableViewController, ProgressAlertHandler {
         logger.error("no documents directory found")
     }
 
-    private func emptyServer() {
-        let alert = UIAlertController(title: String.localized("pref_empty_server_title"),
-                                      message: String.localized("pref_empty_server_msg"), preferredStyle: .safeActionSheet)
-        alert.addAction(UIAlertAction(title: String.localized("pref_empty_server_inbox"), style: .destructive, handler: { _ in
-            self.emptyServer2ndConfirm(title: String.localized("pref_empty_server_inbox"), flags: Int(DC_EMPTY_INBOX))
-        }))
-        alert.addAction(UIAlertAction(title: String.localized("pref_empty_server_mvbox"), style: .destructive, handler: { _ in
-            self.emptyServer2ndConfirm(title: String.localized("pref_empty_server_mvbox"), flags: Int(DC_EMPTY_MVBOX))
-        }))
-        alert.addAction(UIAlertAction(title: String.localized("cancel"), style: .cancel))
-        present(alert, animated: true, completion: nil)
-    }
-
-    private func emptyServer2ndConfirm(title: String, flags: Int) {
-        let alert = UIAlertController(
-            title: title,
-            message: String.localized("pref_empty_server_msg"), preferredStyle: .alert)
-        alert.addAction(UIAlertAction(title: String.localized("pref_empty_server_do_button"), style: .destructive, handler: { _ in
-            self.dcContext.emptyServer(flags: flags)
-        }))
-        alert.addAction(UIAlertAction(title: String.localized("cancel"), style: .cancel))
-        present(alert, animated: true, completion: nil)
-    }
-
     private func deleteAccount() {
         guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
             return