You may have accidentally downloaded the Ask toolbar on your computer. The Ask Toolbar is a search engine and toolbar available with other free programs like Java or an Adobe update. It therefore replaces your default search engine and your home page will be search.ask.com. To remove this toolbar from Chrome, you can try to remove it through Chrome options, but it may be necessary to use other techniques.
Steps
Method 1 of 4: Remove Ask Toolbar from Chrome

Step 1. Click the Chrome menu button in the browser toolbar, select Tools then click on Extensions.

Step 2. Select the Extensions tab.

Step 3. Eliminate the Ask toolbar by clicking on the small trash can next to it

Step 4. Click on the Chrome menu button again

Step 5. Click Settings

Step 6. Select Manage Search Engines
It's in the Research section.

Step 7. Configure Chrome's default search engine on Google.com by clicking Use Default and select Google

Step 8. Look for Ask
com in the search engine list. Delete it by clicking on X.
Method 2 of 4: Remove the Ask Toolbar if the above method doesn't work

Step 1. See if you get the following message on the Extensions page
“This extension is managed and cannot be uninstalled or deactivated."

Step 2. Close Chrome

Step 3. Right click on an empty area of the taskbar

Step 4. Select Task Manager

Step 5. Click the Processes tab
See if chrome.exe * 32 is running and select it if it is.

Step 6. Click End Process

Step 7. Open the Control Panel

Step 8. Select Programs and Features
It can also be Add and remove programs or simply Programs (depending on your operating system). For Windows 8 users, right click in the lower left corner and select Control panel then select Uninstall a program.

Step 9. Uninstall the Ask Toolbar and its Update

Step 10. Restart your computer

Step 11. Go to Disk Cleanup
You can search for this option in the search box by clicking on the Windows Start menu.

Step 12. Select your hard drive (probably C)

Step 13. Click OK to clean the disk out
Wait while the operation completes.

Step 14. Click on the Chrome menu

Step 15. Select Settings

Step 16. Click Show advanced settings

Step 17. Choose Content Settings
It's in the "Confidentiality" section.

Step 18. Delete all cookies in the “Cookies and site data” section
Method 3 of 4: Scan with antivirus software

Step 1. Download Malwarebytes for free
You can find it at malwarebytes.org/products/malwarebytes_free/ to make sure there is no more malware on your computer.

Step 2. Double-click to install the program

Step 3. Keep the default settings

Step 4. Click Finish

Step 5. Select Perform a quick scan

Step 6. Click Scanner

Step 7. Wait for the scan to finish, then click View Results

Step 8. Locate the malware discovered as a result, select all and click Remove
Method 4 of 4: Remove the Ask toolbar with the tool from Ask.com

Step 1. Download the tool from Ask.com
apnmedia.ask.com/media/toolbar/utilities/ToolbarRemover.exe.

Step 2. Close the Chrome browser

Step 3. Run the cleaner you downloaded

Step 4. Restart Chrome

Step 5. Observe that the Ask extension is now gone
Advice
- Make sure you never intentionally install the Ask Toolbar.
- The Ask toolbar is included with Java. You need to be very careful during the installation process to avoid installing it while you are installing or updating Java.