How to reduce a multi-index pandas dataframe to single-index?

Question

I ave acquired a pandas dataframe that has a multi-index via the code below:

price_data = yf.dpwnload(tickers = tickers_str, period = "2y", interval = "1wk", group_by = 'ticker')

The acquired dataframe is shown in the image below.

How can I turn this dataframe into single-index?

Columns of dataset:

        ( 'SOKM.IS',   'Open'),
        ( 'SOKM.IS',   'Close'),
        ('EGEEN.IS',   'Open'),
        ('EGEEN.IS',  'Close'),...

Desired output:

• Column name must be the first index (i.e. "SOKM.IS", "EGEEN.IS", etc.)
• value must be the value at "Close" index of 2nd index