As far as I am aware, the only place for resizing images is under the export menu, which you can access from the file menu or by right clicking the image you want to export, then selecting export or there is also a keyboard short cut. From here you will get the option to export a version or the original file. I am usually exporting versions (after adjustments).

This opens up a dialogue box and from here you select where you would like to save the exported file. It is also here that you set the file type and size.

First item in the dialogue is Export Preset, click this drop down and you will see all the options available (Jpeg, TIFF, PNG, PSD etc). There are some default presets included but you can also edit those to change the size & quality of the file or even create your own.

Hope this helps