I tried:
WebDriverWait(driver, 10).until(EC.element_to_be_clickable((By.XPATH,"//*[@value='Sign Out']"))) 
but no luck.. please see image for the html script

I tried:
WebDriverWait(driver, 10).until(EC.element_to_be_clickable((By.XPATH,"//*[@value='Sign Out']"))) 
but no luck.. please see image for the html script

 
    
     
    
    The desired element is a JavaScript enabled element so to click on the element you have to induce WebDriverWait for the element_to_be_clickable() and you can use either of the following Locator Strategies:
Using CSS_SELECTOR and click():
WebDriverWait(driver, 20).until(EC.element_to_be_clickable((By.CSS_SELECTOR, "form[action*='Logoff']>li>input[value='Sign Out']"))).click()
Using XPATH and submit():
WebDriverWait(driver, 20).until(EC.element_to_be_clickable((By.XPATH, "//form[contains(@action, 'Logoff')]/li/input[@value='Sign Out']"))).submit()
Note : You have to add the following imports :
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.common.by import By
from selenium.webdriver.support import expected_conditions as EC
