Please see attached spreadsheet providing a method to remove outliers using excel. Here we test for leverage points and remove data.

You can apply some basic clustering techniques i.e. k-means, DBSCAN and so on for the outlier detection and removal.

You can use the box plot and scatter plot that employs quartile in excel to determine the outliers.

Dear Dhani Shanker Chaubey

You can use trend analysis on the data set. I mean, Ratio trend variation method can be used for outlier detection and removal of it.

Thanks