Steps are given below
On the View tab, in the Presentation Views group, click Slide Master.
In the pane that contains the slide masters and layouts, locate and click the Blank Layout in the list of thumbnail layouts below the slide master.
To modify the layout, do one or more of the following:
To remove unwanted, default placeholders such as headers, footers, or the date and time, click the border of the placeholder, and then press DELETE.
To add a placeholder, do the following:
On the Slide Master tab, in the Master Layout group, click Insert Placeholder, and then select a placeholder type from the list.
Click a location on the layout, and then drag to draw the placeholder.

Tip To resize a placeholder, drag one of its corner borders.
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In the thumbnail list of layouts, right-click the Blank Layout and then click Rename Layout.
In the Rename Layout dialog box, type a new name that describes the new layout you've just customized, and then click Rename.

Click the Microsoft Office Button Button image, and then click Save As.
In the File name box, type a file name, or do nothing to accept the suggested file name.
In the Save as type list, click PowerPoint Template, and then click Save.