How do I remove blank pages coming between two chapters in Appendix?

Your problem is that all chapters, whether they're in the appendix or not, default to starting on an odd-numbered page when you're in two-sided layout mode. A few possible solutions:

The simplest solution is to use the openany option to your document class, which makes chapters start on the next page, irrespective of whether it's an odd or even numbered page. This is supported in the standard book documentclass, eg \documentclass[openany]{book}. (memoir also supports using this as a declaration \openany which can be used in the middle of a document to change the behavior for subsequent pages.)

Another option is to try the \let\cleardoublepage\clearpage command before your appendices to avoid the behavior.

Or, if you don't care using a two-sided layout, using the option oneside to your documentclass (eg \documentclass[oneside]{book}) will switch to using a one-sided layout.

it is very easy:

add \documentclass[oneside]{book} and youre fine ;)