```
\documentclass{article}
\usepackage{amsmath,amsthm,amssymb,parskip}
\usepackage{graphicx,float,hyperref}
\usepackage[margin=1in]{geometry}
\usepackage{titling,multicol}
\usepackage{tcolorbox}
\tcbuselibrary{theorems}
\newtcbtheorem{mytheo*}{}%
{colback=purple!5,colframe=blue!100!,fonttitle=\bfseries}{th}
\begin{document}
\begin{mytheo*}{title...}{}
text...
\end{mytheo*}
\end{document}
```

I am trying to make the theorem unnumbered, but I have not managed to figure out how to remove the number 1 and the colon that appear at the beginning of the theorem title. Does anyone know how to do this?

## Best Answer

There is a misunderstanding by the OP what

`\newtcbtheorem`

does actually:`\newtcbtheorem{foo}{...}{...}{...}`

will actually define both the numbered theorem - like enviroment`foo`

and`foo*`

, so`\newtcbtheorem{foo*}`

will actually define`foo*`

and`foo**`

, leaving`foo*`

being numbered however and`foo**`

is the unnumbered version.See page 340 of current

`tcolorbox`

manual for a description of this.In addition,

`hyperref`

should be loaded as last package as almost always in 98% of all cases.As a reply to the comment below by Bryan-M-H:

The unstarred version of the theorem has an additional mandatory argument that is meant for the label, see the changed example where the label is given as

`{foo}`

, which is extended to`th:foo`

since the definition of the theorem has`th`

as label prefix.Related (but not duplicate) Counter for tcolorbox

Also related (no duplicate too): Problem with tcolorbox package