Then how can we bring back in editable mode? where we can change size etc?
Please consider reviewing some basic tutorials:
Get to know Photoshop from Adobe
This is really core knowledge regarding the application functionality. Reviewing basic tutorials will assist you in working more quickly rather than having to post questions about basic functionality.
To resize content on a layer...
Highlight the layer in the Layers Panel then choose
Edit > Free Transform or
Edit > Transform > [whatever option you want]