diff --git a/CHANGELOG.md b/CHANGELOG.md
index 04dfd9e..025fb9c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## [x.y.z](https://github.com/sushichop/Puppy/releases/tag/x.y.z) (yyyy-mm-dd)
+
+- Remove concurrency features. [#39](https://github.com/sushichop/Puppy/pull/39)
+
 ## [0.4.0](https://github.com/sushichop/Puppy/releases/tag/0.4.0) (2022-01-31)
 
 - `FileRotatonLogger` inherits `FileLogger`. [#29](https://github.com/sushichop/Puppy/pull/29)
diff --git a/Sources/Puppy/FileLogger.swift b/Sources/Puppy/FileLogger.swift
index 02ac1f9..362bade 100644
--- a/Sources/Puppy/FileLogger.swift
+++ b/Sources/Puppy/FileLogger.swift
@@ -68,22 +68,6 @@ public class FileLogger: BaseLogger {
         }
     }
 
-    #if compiler(>=5.5.2)
-    @available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
-    public func delete(_ url: URL) async throws -> URL {
-        try await withCheckedThrowingContinuation { continuation in
-            queue!.async {
-                do {
-                    try FileManager.default.removeItem(at: url)
-                    continuation.resume(returning: url)
-                } catch {
-                    continuation.resume(throwing: FileDeletingError.failed(at: url))
-                }
-            }
-        }
-    }
-    #endif
-
     public func flush() {
         queue!.sync {
             fileHandle?.synchronizeFile()
@@ -96,17 +80,6 @@ public class FileLogger: BaseLogger {
         }
     }
 
-    #if compiler(>=5.5.2)
-    @available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
-    public func flush() async {
-        await withCheckedContinuation { continuation in
-            queue!.async {
-                continuation.resume()
-            }
-        }
-    }
-    #endif
-
     func openFile() throws {
         closeFile()
         let directoryURL = fileURL.deletingLastPathComponent()
diff --git a/Tests/PuppyTests/FileLoggerTests.swift b/Tests/PuppyTests/FileLoggerTests.swift
index 5e597fe..1d64157 100644
--- a/Tests/PuppyTests/FileLoggerTests.swift
+++ b/Tests/PuppyTests/FileLoggerTests.swift
@@ -180,30 +180,6 @@ final class FileLoggerTests: XCTestCase {
         wait(for: [expSuccess, expFailure], timeout: 5.0)
     }
 
-    #if compiler(>=5.5.2)
-    @available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
-    func testDeletingFileAsyncAwait() async throws {
-        let existentFileURL = URL(fileURLWithPath: "./existent-async-await.log").absoluteURL
-        let noExistentFileURL = URL(fileURLWithPath: "./no-existent-async-await.log").absoluteURL
-        let fileLogger = try FileLogger("com.example.yourapp.filelogger.deletingasyncawait", fileURL: existentFileURL)
-
-        do {
-            let url = try await fileLogger.delete(existentFileURL)
-            XCTAssertEqual(url, existentFileURL)
-        } catch {
-            XCTFail("error should not be thrown, but it was thrown: \(error.localizedDescription)")
-        }
-
-        do {
-            _ = try await fileLogger.delete(noExistentFileURL)
-            XCTFail("error should be thrown while awaiting, but it was not thrown")
-        } catch {
-            XCTAssertEqual(error as? FileDeletingError, .failed(at: noExistentFileURL))
-            XCTAssertEqual(error.localizedDescription, "failed to delete the file: \(noExistentFileURL)")
-        }
-    }
-    #endif
-
     func testFlushFile() throws {
         let flushFileURL = URL(fileURLWithPath: "./flush.log").absoluteURL
         let fileLogger = try FileLogger("com.example.yourapp.filelogger.flush", fileURL: flushFileURL, flushMode: .manual)
@@ -238,22 +214,6 @@ final class FileLoggerTests: XCTestCase {
         wait(for: [exp], timeout: 5.0)
     }
 
-    #if compiler(>=5.5.2)
-    @available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
-    func testFlushFileAsyncAwait() async throws {
-        let fileURL = URL(fileURLWithPath: "./flush-async-await.log").absoluteURL
-        let fileLogger = try FileLogger("com.example.yourapp.filelogger.flushasyncawait", fileURL: fileURL, flushMode: .manual)
-        let log = Puppy()
-        log.add(fileLogger)
-        log.trace("flushAsyncAwait, TRACE message using FileLogger")
-        log.verbose("flushAsyncAwait, VERBOSE message using FileLogger")
-
-        await fileLogger.flush()
-        _ = try await fileLogger.delete(fileURL)
-        log.remove(fileLogger)
-    }
-    #endif
-
     func testFilePermssion() throws {
         let fileURL = URL(fileURLWithPath: "./permisson600.log").absoluteURL
         let fileLogger = try FileLogger("com.example.yourapp.filelogger.permisson600", fileURL: fileURL, filePermisson: "600")