Step 1.

Head to your theme files and explore the following two folders:

./assets/

./snippets/

in both these folders, delete each of the files with the prefix

____clspeedapp

Step 2.

Head to your theme.liquid file, and remove 

2.1 - At the top of the file remove the following 4 lines:

<!-- crazy-load LOAD CONFIG -->
{% include '__clspeedapp-theme-config' %}

<!-- crazy-load BEGIN CAPTURE -->
{%- capture __clspeedapp-html -%}

2.2 - Right under <head> remove the following block:

<!-- crazy-load BEGIN HEAD TOP -->
{% include '__clspeedapp-theme-preload' %}
{% include '__clspeedapp-html-css' %}
{% include '__clspeedapp-html-css-critical' %}

{% include '__clspeedapp-js-init' %}
{% include '__clspeedapp-js-functions' %}

{%- unless is_admin_interface -%}
{% include '__clspeedapp-js-frontend' %}
{%- endunless -%}

{%- unless is_admin_interface -%}
{% include '__clspeedapp-js-scripts' %}
{%- endunless -%}
<!-- crazy-load END HEAD TOP -->

2.3 - Right before the closing </body> tag, remove this block:

<!-- crazy-load BEGIN BODY -->
{% include '__clspeedapp-html-fonts' %}
<!-- crazy-load END BODY -->

2.4 - and finally, right after the closing </html> tag, remove this block:

<!-- crazy-load END CAPTURE -->
{%- endcapture -%}

<!-- crazy-load LOAD HTML -->
{% include '__clspeedapp-theme-html' %}

That's it! You've successfully remove all the CrazyLoad code manually from your theme.